vtorc: use *topoprotopb.TabletAlias for tablet alias

[timvaillancourt]

Description

This PR refactors VTOrc to use *topoprotopb.TabletAlias (vs a topoproto.TabletAliasString(...)-encoded string) to reference a tablet throughout the code

Currently the VTOrc encode/decodes string-based tablet aliases using topoproto.TabletAliasString(...) and topoproto.ParseTabletAlias(...). This PR continues to do this same conversion, but only in places where it is required, lower in the code:

1. The sqlite backend - we need to encode structs as strings in sqlite
2. Logging that refers to tablet alias - the .String() method on *topoprotopb.TabletAlias produces a weird prototext format so topoproto.TabletAliasString(...)-encoded string is still used
3. Cache library keys (string)

Finally, a huge if block was moved to switch in inst.GetDetectionAnalysis

This change aids in the implementation of these RFCs:

1. RFC: gRPC server for VTOrc APIs #18251 - implementing a gRPC server will mean the code will move to using protobuf-based data. So more of the code will be referring to things as real *topoprotopb.TabletAlias (that's my plan at least)
2. RFC: access data via an interface in vtorc #17190 - having to decode/encode tablet aliases as string is really just an implementation detail of the current sqlite backend. Future backends don't need to be hindered by this, so lets use function signatures that use real *topoprotopb.TabletAlias

Related Issue(s)

1. RFC: gRPC server for VTOrc APIs #18251
2. RFC: access data via an interface in vtorc #17190

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]

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[codecov]

Codecov Report

❌ Patch coverage is 39.01345% with 136 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.89%. Comparing base (e48c2d5) to head (2a2c5eb).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vtorc/logic/topology_recovery.go	0.00%	36 Missing ⚠️
go/vt/vtorc/logic/tablet_discovery.go	0.00%	20 Missing ⚠️
go/vt/vtorc/logic/vtorc.go	5.00%	19 Missing ⚠️
go/vt/vtorc/logic/discovery_queue.go	0.00%	16 Missing ⚠️
go/vt/vtorc/server/api.go	5.88%	16 Missing ⚠️
go/vt/vtorc/inst/instance_dao.go	77.94%	15 Missing ⚠️
go/vt/vtorc/logic/topology_recovery_dao.go	0.00%	13 Missing ⚠️
go/vt/vtorc/inst/shard_dao.go	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #18389      +/-   ##
==========================================
- Coverage   69.90%   69.89%   -0.02%     
==========================================
  Files        1612     1612              
  Lines      215796   215832      +36     
==========================================
- Hits       150858   150845      -13     
- Misses      64938    64987      +49     

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[github-actions]

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[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

• Push additional commits to the associated branch.
• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.

[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

• Push additional commits to the associated branch.
• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.