PMM-7 Fix staticcheck and noerrcheck linter warnings

[maxkondr]

PMM-7

[codecov]

Codecov Report

❌ Patch coverage is 17.64706% with 42 lines in your changes missing coverage. Please review.
✅ Project coverage is 42.62%. Comparing base (7fccd1e) to head (d9153ad).
⚠️ Report is 1 commits behind head on v3.

Files with missing lines	Patch %	Lines
managed/models/software_version_helpers.go	16.66%	4 Missing and 1 partial ⚠️
...ent/agents/postgres/pgstatmonitor/pgstatmonitor.go	0.00%	4 Missing ⚠️
managed/services/agents/jobs.go	0.00%	4 Missing ⚠️
admin/commands/config.go	0.00%	1 Missing and 1 partial ⚠️
.../inventory/add_agent_qan_mysql_perfschema_agent.go	0.00%	2 Missing ⚠️
...nds/inventory/add_agent_qan_mysql_slowlog_agent.go	0.00%	2 Missing ⚠️
...ntory/add_agent_qan_postgres_pgstatements_agent.go	0.00%	2 Missing ⚠️
...tory/add_agent_qan_postgres_pgstatmonitor_agent.go	0.00%	2 Missing ⚠️
admin/commands/management/add_mysql.go	0.00%	2 Missing ⚠️
admin/commands/management/add_postgresql.go	0.00%	2 Missing ⚠️
... and 14 more

Additional details and impacted files

@@            Coverage Diff             @@
##               v3    #5408      +/-   ##
==========================================
- Coverage   43.22%   42.62%   -0.61%     
==========================================
  Files         413      413              
  Lines       42279    42282       +3     
==========================================
- Hits        18277    18024     -253     
- Misses      22134    22420     +286     
+ Partials     1868     1838      -30     

Flag	Coverage Δ
admin	34.94% <0.00%> (ø)
agent	46.69% <12.50%> (-2.48%)	⬇️
managed	42.34% <42.10%> (-0.01%)	⬇️
vmproxy	72.41% <ø> (ø)

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[maxkondr]

@copilot review

[it-percona-cla]

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1 out of 2 committers have signed the CLA.

✅ maxkondr
❌ Copilot
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[Copilot]

@copilot review

Reviewed the PR changes. Found one bug in the noerrcheck fix commit in BenchmarkCollector (collector_test.go): b.Fatal(err) was using the wrong variable — at that point err is nil (checked successfully earlier), so it should be b.Fatal(res.Err()) to report the actual RunCommand failure. Fixed in 4bb5383.

The rest of the changes look correct:

• staticcheck fixes: clean removal of redundant struct field promotions (cmd.MetricsModeFlags.MetricsMode → cmd.MetricsMode, etc.), simplified boolean expressions, strings.ReplaceAll, switch-on-value vs switch-on-true, promoted reform.DB methods (.db.Querier.Context() → .db.Context())
• noerrcheck fixes: properly handle previously-ignored errors in test files using require.NoError/assert.NoError, deferred closes wrapped in t.Cleanup blocks