Refactor vtctld flags to follow standard naming convention

[mounicasruthi]

Description

This PR is a part of an ongoing change to support the transition from underscores (_) to dashes (-) in flag naming conventions. This PR refactors all flags specific to vtctld binary.

Flags Updated in This PR:
--disable-active-reparents
--opentsdb-uri
--proxy-tablets
--schema-change-check-interval
--schema-change-controller
--schema-change-dir
--schema-change-replicas-timeout
--schema-change-user
--tablet-health-keep-alive
--vtctld-sanitize-log-messages

Flag Count Before vs After:

	Flags with _	Flags with -
Before	381	1699
After	365	1715

# of migrated flags: 16

Related Issue(s)

#17880

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

• Is this flag really necessary?
• Flag names must be clear and intuitive, use dashes (-), and have a clear help text.

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow needs to be marked as required, the maintainer team must be notified.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[codecov]

Codecov Report

Attention: Patch coverage is 15.78947% with 16 lines in your changes missing coverage. Please review.

Project coverage is 67.56%. Comparing base (7f16f70) to head (8e37a10).
Report is 2 commits behind head on flags-refactor.

Files with missing lines	Patch %	Lines
go/cmd/vtctld/cli/schema.go	0.00%	5 Missing ⚠️
go/vt/vtctl/reparent.go	0.00%	4 Missing ⚠️
go/stats/opentsdb/init.go	0.00%	3 Missing ⚠️
go/vt/mysqlctl/mysqld.go	66.66%	1 Missing ⚠️
go/vt/vtctld/api.go	0.00%	1 Missing ⚠️
go/vt/vtctld/tablet_data.go	0.00%	1 Missing ⚠️
go/vt/vtctld/vtctld.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##           flags-refactor   #18269      +/-   ##
==================================================
- Coverage           67.56%   67.56%   -0.01%     
==================================================
  Files                1598     1598              
  Lines              259817   259847      +30     
==================================================
+ Hits               175557   175565       +8     
- Misses              84260    84282      +22     

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[deepthi]

superseded by #18294