chore(logs): modifying the capitalization consistency of the logs - Part 3

[pangruoran]

What this PR does / why we need it:

Which issue this PR fixes:
part of #3708

Special notes for your reviewer:

It has been split from PR #4992 to make it easier to review.

This PR include two part:

• sed -i 's/failed to/Failed to/g'
• sed -i 's/could not/Could not/g'

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

Attention: 55 lines in your changes are missing coverage. Please review.

Comparison is base (dce791d) 75.5% compared to head (a20b269) 75.6%.
Report is 8 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5037   +/-   ##
=====================================
  Coverage   75.5%   75.6%           
=====================================
  Files        167     167           
  Lines      18848   18881   +33     
=====================================
+ Hits       14238   14278   +40     
+ Misses      3783    3779    -4     
+ Partials     827     824    -3     

Files	Coverage Δ
...nal/controllers/configuration/secret_controller.go	56.0% <100.0%> (ø)
internal/dataplane/failures/failures.go	100.0% <100.0%> (ø)
internal/dataplane/kong_client.go	89.5% <100.0%> (-0.1%)	⬇️
internal/dataplane/parser/ingressrules.go	95.1% <100.0%> (ø)
internal/license/agent.go	90.8% <100.0%> (ø)
internal/admission/handler.go	61.0% <80.0%> (+1.5%)	⬆️
internal/admission/server.go	42.0% <0.0%> (ø)
internal/clients/readiness.go	89.1% <0.0%> (ø)
internal/controllers/reference/reference.go	50.5% <0.0%> (ø)
internal/dataplane/parser/parser.go	92.0% <66.6%> (+0.7%)	⬆️
... and 20 more

... and 1 file with indirect coverage changes

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