internal/xds: change xds_resolver to use dependency manager

[eshitachandwani]

This change is part of A74 implementation.

This PR removes the listener and route watchers from resolver and changes it so that we get the resources from xds dependency manager.

RELEASE NOTES:

• xds/resolver:
  • Changes the behavior such that getting no matching virtual host in a route resource will now drop any previous resource and report the error.
  • Changes the behavior so that receiving a configuration error (LDS/RDS ambient error) after a successful update will now only be logged, and the system will continue using the previous resource to avoid transient channel failures

[codecov]

Codecov Report

❌ Patch coverage is 81.39535% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.20%. Comparing base (08d0792) to head (70b91fa).
⚠️ Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/xds/resolver/xds_resolver.go	81.39%	5 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8711      +/-   ##
==========================================
- Coverage   83.31%   83.20%   -0.11%     
==========================================
  Files         419      418       -1     
  Lines       32429    32356      -73     
==========================================
- Hits        27017    26922      -95     
- Misses       4038     4049      +11     
- Partials     1374     1385      +11     

Files with missing lines	Coverage Δ
internal/xds/resolver/xds_resolver.go	88.57% <81.39%> (+6.14%)	⬆️

... and 35 files with indirect coverage changes

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[easwars]

Is the PR description out of date? I don't see any changes about switching the dependency manager to use the serializer again.

[eshitachandwani]

Is the PR description out of date? I don't see any changes about switching the dependency manager to use the serializer again.

Yeah sorry , I was making that change earlier but Arjan suggested a different way, so that got changed.

[arjan-bal]

This comment probably needs to be updated since the resolver doesn't report an error for ambient listener and route errors anymore.

[eshitachandwani]

Done.

[arjan-bal]

LGTM