chore: change subject name from no_name to named for PNGs in

[AAfghahi]

SUMMARY

Previously images in reports or alerts looked like this:

this PR changes them to have this:
[chart or dashboard name] [date of screenshot].png

After:

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #19929 (2a44304) into master (1fa841e) will decrease coverage by 0.15%.
The diff coverage is 100.00%.

❗ Current head 2a44304 differs from pull request most recent head a8c2f16. Consider uploading reports for the commit a8c2f16 to get more accurate results

@@            Coverage Diff             @@
##           master   #19929      +/-   ##
==========================================
- Coverage   66.51%   66.35%   -0.16%     
==========================================
  Files        1715     1715              
  Lines       65060    65063       +3     
  Branches     6723     6723              
==========================================
- Hits        43272    43170     -102     
- Misses      20076    20181     +105     
  Partials     1712     1712              

Flag	Coverage Δ
hive	?
mysql	?
postgres	81.99% <100.00%> (?)
presto	?
python	82.03% <100.00%> (-0.33%)	⬇️
sqlite	81.75% <100.00%> (+<0.01%)	⬆️
unit	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/datasets/dao.py	93.79% <100.00%> (ø)
superset/utils/core.py	89.74% <100.00%> (-0.09%)	⬇️
superset/db_engines/hive.py	0.00% <0.00%> (-85.19%)	⬇️
superset/db_engine_specs/hive.py	70.11% <0.00%> (-15.71%)	⬇️
superset/common/utils/dataframe_utils.py	85.71% <0.00%> (-7.15%)	⬇️
superset/db_engine_specs/presto.py	83.36% <0.00%> (-5.34%)	⬇️
superset/db_engine_specs/mysql.py	93.97% <0.00%> (-3.62%)	⬇️
superset/connectors/sqla/models.py	88.84% <0.00%> (-1.20%)	⬇️
superset/models/core.py	88.38% <0.00%> (-0.95%)	⬇️
superset/views/core.py	76.61% <0.00%> (-0.45%)	⬇️
... and 10 more

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[AAfghahi]

/testenv up FEATURE_ALERT_REPORTS=True

[github-actions]

@AAfghahi Ephemeral environment spinning up at http://54.214.133.2:8080. Credentials are admin/admin. Please allow several minutes for bootstrapping and startup.

[eschutho]

what's the difference between this line, and what we're doing in line 937?

[AAfghahi]

good question, I am running it now without the file in image to see. The documentation used both so I emulated and then wasn't able to properly test until just recently.

[AAfghahi]

Ok, I tested, and the add_header line seems inconsequential to the process that we want, so I deleted it.

[jinghua-qa]

screenshot looks good to me!

[github-actions]

Ephemeral environment shutdown and build artifacts deleted.