PMM-13416 Fix enum flags in pmm-admin.

[BupycHuk]

PMM-13416

Link to the Feature Build: SUBMODULES-3737

If this PR adds or removes or alters one or more API endpoints, please review and add or update the relevant API documents as well:

• API Docs updated

If this PR is related to some other PRs in this or other repositories, please provide links to those PRs:

• Links to related pull requests (optional).

[codecov]

Codecov Report

Attention: Patch coverage is 2.50000% with 39 lines in your changes missing coverage. Please review.

Project coverage is 43.45%. Comparing base (50d1e9a) to head (e4f8742).

Files with missing lines	Patch %	Lines
admin/pkg/flags/loglevel.go	0.00%	4 Missing ⚠️
admin/commands/management/add_mysql.go	0.00%	3 Missing ⚠️
admin/commands/management/add_postgresql.go	0.00%	3 Missing ⚠️
.../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_mongodb.go	0.00%	2 Missing ⚠️
admin/commands/management/add_proxysql.go	0.00%	2 Missing ⚠️
admin/pkg/flags/comments_parsing.go	0.00%	2 Missing ⚠️
... and 13 more

Additional details and impacted files

@@            Coverage Diff             @@
##               v3    #3236      +/-   ##
==========================================
- Coverage   43.45%   43.45%   -0.01%     
==========================================
  Files         360      363       +3     
  Lines       43977    43934      -43     
==========================================
- Hits        19112    19090      -22     
+ Misses      23204    23182      -22     
- Partials     1661     1662       +1     

Flag	Coverage Δ
admin	11.53% <2.70%> (+0.04%)	⬆️
agent	51.93% <0.00%> (ø)
managed	45.16% <0.00%> (-0.01%)	⬇️

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