fix: send mail only if SMTP was configured(Event Export)

[mrsaicharan1]

Fixes #6158

Short description of what this resolves:

When sending an email fails, the event export fails with a message saying that the export failed, which is not expected.

Changes proposed in this pull request:

• Checked SMTP config before calling export_mail
• Logged appropriate warnings

Checklist

• I have read the Contribution & Best practices Guide and my PR follows them.
• My branch is up-to-date with the Upstream development branch.
• The unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

• All the functions created/modified in this PR contain relevant docstrings.

[codecov]

Codecov Report

Merging #6228 into development will decrease coverage by 0.02%.
The diff coverage is 12.5%.

@@               Coverage Diff               @@
##           development    #6228      +/-   ##
===============================================
- Coverage        65.71%   65.69%   -0.03%     
===============================================
  Files              286      286              
  Lines            14523    14529       +6     
===============================================
+ Hits              9544     9545       +1     
- Misses            4979     4984       +5

Impacted Files	Coverage Δ
app/api/helpers/tasks.py	17.56% <12.5%> (-0.02%)	⬇️

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[mrsaicharan1]

@iamareebjamal @shreyanshdwivedi @uds5501 Please review