telemetry: remove the codes of Telemetry

[bb7133]

What problem does this PR solve?

Issue Number: close #49939

Problem Summary:

What changed and how does it work?

As is described.

Configuration 'enable-telemetry' and the system variable 'tidb_enable_telemetry' are kept for compatibility consideration, but they're both deprecated after this PR: the values of them are meanningless.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

Deprecate Telemetry for TiDB:
* Deprecate configuration '[enable-telemetry](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#enable-telemetry-new-in-v402)' and the system variable '[tidb_enable_telemetry](https://docs.pingcap.com/tidb/stable/system-variables#tidb_enable_telemetry-new-in-v402)': the values of them are meaningless now.
* Remove all SQL syntax of Telemetry, including `ADMIN SHOW TELEMETRY` and `ADMIN RESET TELEMETRY_ID`.
* Remove `TELEMETRY` and `TELEMETRY_ID` from TiDB unreserved keywords list.

[codecov]

Codecov Report

Merging #51202 (ae44e66) into master (4c76b12) will decrease coverage by 15.4495%.
Report is 14 commits behind head on master.
The diff coverage is 100.0000%.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #51202         +/-   ##
=================================================
- Coverage   70.5887%   55.1393%   -15.4495%     
=================================================
  Files          1467       1577        +110     
  Lines        434905     607140     +172235     
=================================================
+ Hits         306994     334773      +27779     
- Misses       108649     249426     +140777     
- Partials      19262      22941       +3679     

Flag	Coverage Δ
integration	36.8545% <84.6153%> (?)
unit	70.9493% <100.0000%> (+0.5644%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	51.6857% <ø> (+5.8177%)	⬆️

[windtalker]

LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-02-21 22:10:14.606216407 +0000 UTC m=+481503.353839518: ☑️ agreed by ngaut.
• 2024-02-22 03:20:23.857274189 +0000 UTC m=+500112.604897300: ☑️ agreed by windtalker.

[Benjamin2037]

LGTM

[lance6716]

/approve

for lightning and domain

[BornChanger]

br part lgtm

[wuhuizuo]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Benjamin2037, BornChanger, lance6716, ngaut, windtalker, zimulala Once this PR has been reviewed and has the lgtm label, please assign d3hunter, easonn7 for approval. For more information see the Kubernetes Code Review Process.

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Needs approval from an approver in each of these files:

• OWNERS [Benjamin2037,lance6716,ngaut,windtalker,zimulala]
• br/pkg/lightning/OWNERS [Benjamin2037,lance6716]
• pkg/config/OWNERS
• pkg/ddl/OWNERS [Benjamin2037,zimulala]
• pkg/distsql/OWNERS [Benjamin2037,windtalker]
• pkg/domain/OWNERS [lance6716,zimulala]
• pkg/expression/OWNERS [windtalker]
• pkg/parser/OWNERS [BornChanger]

  Need more approvers for rest parts.

• pkg/sessionctx/variable/OWNERS

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@bb7133 rest parts need be approved by d3hunter and easonn7

[easonn7]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Benjamin2037, BornChanger, easonn7, lance6716, ngaut, windtalker, zimulala

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [Benjamin2037,lance6716,ngaut,windtalker,zimulala]
• br/pkg/lightning/OWNERS [Benjamin2037,lance6716]
• pkg/config/OWNERS [easonn7]
• pkg/ddl/OWNERS [Benjamin2037,zimulala]
• pkg/distsql/OWNERS [Benjamin2037,windtalker]
• pkg/domain/OWNERS [lance6716,zimulala]
• pkg/expression/OWNERS [windtalker]
• pkg/parser/OWNERS [BornChanger,easonn7]
• pkg/sessionctx/variable/OWNERS [easonn7]

Approvers can indicate their approval by writing /approve in a comment
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