fix(db): split advisors session setup from lint query

[jsj]

Fixes #4965.

Summary

• split the local advisors session setup from the embedded lint query
• execute set local search_path = '' separately before running the lint SQL
• update advisors tests to cover the split query path and setup failure handling

Validation

• go test ./internal/db/advisors
• verified against a live local Supabase project

[coveralls]

Pull Request Test Coverage Report for Build 23214527521

Details

• 9 of 11 (81.82%) changed or added relevant lines in 1 file are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.01%) to 61.877%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/db/advisors/advisors.go	9	11	81.82%

Files with Coverage Reduction	New Missed Lines	%
internal/utils/git.go	5	57.14%

Totals
Change from base Build 23201604318:	0.01%
Covered Lines:	8039
Relevant Lines:	12992

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💛 - Coveralls

[Rodriguespn]

Thanks for taking a look at this @jsj