Fixed image parsing logic

[neel-astro]

Description

Changes:

• Fixed logic with parsing image name from Dockerfile to fix issues with ports being in hostname, panic when no tag is present.

🎟 Issue(s)

Related astronomer/issues#926
Related astronomer/issues#3473
Related astronomer/issues#3605

🧪 Functional Testing

List the functional testing steps to confirm this feature or fix.

📸 Screenshots

Add screenshots to illustrate the validity of these changes.

📋 Checklist

• Rebased from the main (or release if patching) branch (before testing)
• Ran make test before taking out of draft
• Added/updated applicable tests
• Tested against Houston-API and Astronomer (if necessary).
• Communicated to/tagged owners of respective clients potentially impacted by these changes.
• Updated any related documentation

[andriisoldatenko]

you can avoid else here:

tag = "latest"
if ok {
     tag = parsedTag.Tag()
}

[neel-astro]

good point, updated 👍

[codecov]

Codecov Report

Merging #470 (b65dd0e) into main (4ad198a) will increase coverage by 0.05%.
The diff coverage is 84.61%.

@@            Coverage Diff             @@
##             main     #470      +/-   ##
==========================================
+ Coverage   64.59%   64.65%   +0.05%     
==========================================
  Files          42       42              
  Lines        3548     3559      +11     
==========================================
+ Hits         2292     2301       +9     
- Misses       1093     1094       +1     
- Partials      163      164       +1     

Impacted Files	Coverage Δ
docker/parse.go	85.45% <84.61%> (-0.91%)	⬇️

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