VTOrc optimize TMC usage

[GuptaManan100]

Description

This PR implements the feature requested in #15355.

Similar changes to the CheckThrottler RPC had been made in #14979. This PR replicates them for FullStatus RPC. While working on this, a few more refactoring changes have been made to make the code more uniform.

Related Issue(s)

• Fixes Feature Request: Use pooled connection for FullStatus RPC for VTOrc #15355

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

Deployment Notes

[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 10.14493% with 62 lines in your changes are missing coverage. Please review.

Project coverage is 65.42%. Comparing base (696fe0e) to head (bb2faf8).
Report is 54 commits behind head on main.

Files	Patch %	Lines
go/vt/vtorc/inst/instance_dao.go	0.00%	43 Missing ⚠️
go/vt/vttablet/grpctmclient/client.go	46.15%	7 Missing ⚠️
go/vt/vtorc/logic/topology_recovery.go	16.66%	5 Missing ⚠️
go/vt/vtorc/inst/tablet_dao.go	0.00%	4 Missing ⚠️
go/vt/vtorc/logic/tablet_discovery.go	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15356      +/-   ##
==========================================
- Coverage   67.41%   65.42%   -2.00%     
==========================================
  Files        1560     1561       +1     
  Lines      192752   193529     +777     
==========================================
- Hits       129952   126615    -3337     
- Misses      62800    66914    +4114     

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