mysql_role: remove redundant connection closing (fixes #329)

[betanummeric]

fix #329

the connection is already closed during garbage collection: https://github.com/ansible-collections/community.mysql/blob/main/plugins/module_utils/mysql.py#L113-L116

[Andersson007]

@betanummeric hi, yes, i remember @Jorge-Rodriguez implemented that (the garbage collection), thanks for the contribution!
Could you also please add a changelog fragment?

[codecov]

Codecov Report

Merging #330 (15cd0e3) into main (e319ac0) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #330      +/-   ##
==========================================
- Coverage   78.25%   78.24%   -0.01%     
==========================================
  Files          27       27              
  Lines        2249     2248       -1     
  Branches      527      527              
==========================================
- Hits         1760     1759       -1     
  Misses        333      333              
  Partials      156      156              

Impacted Files	Coverage Δ
plugins/modules/mysql_role.py	87.90% <ø> (-0.04%)	⬇️

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[Andersson007]

@betanummeric thanks for the contribution!

[patchback]

Backport to stable-2: 💚 backport PR created

✅ Backport PR branch: patchback/backports/stable-2/641894e6e8fa0c02384e64e7eaaaf5e5e45b82a0/pr-330

Backported as #332

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