VStream API: validate that last PK has fields defined

[rohit-nayak-ps]

Description

The vstream API currently doesn't validate that the Fields for a specified TableLastPK are defined. This results in a panics:

2024-07-16 18:28:49.897	runtime/panic.go:113 (0x436d5e)
2024-07-16 18:28:49.897	vitess.io/vitess/go/sqltypes/result.go:288 (0xcc1fda)
2024-07-16 18:28:49.897	vitess.io/vitess/go/sqltypes/proto3.go:92 (0xcc1e96)
2024-07-16 18:28:49.897	vitess.io/vitess/go/sqltypes/proto3.go:123 (0xcc2210)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer/copy.go:183 (0x15269b2)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer/copy.go:211 (0x1526b97)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer/copy.go:60 (0x152558c)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer/copy.go:39 (0x1525327)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer/uvstreamer.go:418 (0x15390b5)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer/engine.go:236 (0x152969c)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/tabletserver/tabletserver.go:1138 (0x15fc07a)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/vttablet/grpcqueryservice/server.go:336 (0x17f6a47)
2024-07-16 18:28:49.897	vitess.io/vitess/go/vt/proto/queryservice/queryservice_grpc.pb.go:1170 (0x17e9ad2)
2024-07-16 18:28:49.897	google.golang.org/grpc@v1.59.0/server.go:1637 (0xa2a2e3)
2024-07-16 18:28:49.897	google.golang.org/grpc@v1.59.0/server.go:1741 (0xa2bd6f)
2024-07-16 18:28:49.897	google.golang.org/grpc@v1.59.0/server.go:986 (0xa2452b)
2024-07-16 18:28:49.897	runtime/asm_amd64.s:1598 (0x470b60)

This happens because the downstream code converts a query.QueryResult to a sqltypes.Result for which it requires Field type information to be specified.

Since this can crash vttablets we should backport it to all supported versions.

Related Issue(s)

#16479

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

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.62%. Comparing base (f481a77) to head (844ed61).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16478      +/-   ##
==========================================
- Coverage   68.65%   68.62%   -0.03%     
==========================================
  Files        1551     1551              
  Lines      199468   199473       +5     
==========================================
- Hits       136935   136885      -50     
- Misses      62533    62588      +55     

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[GuptaManan100]

LGTM 🚀