chore: refactor Dockerfiles to reduce the build time

[adriang-90]

Checklist:

• [c] Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• I have signed off all my commits as required by DCO
• My build is green (troubleshooting builds).

Summary

I managed to reduce build time by half with those changes. In addition I wanted to make a changes to Dockerfiles that follows the best practices, such as:

• Use WORKDIR instead of RUN mkdir -p
• Reduce number of layers
• Consolidate multiple RUN commands
• Add yarn cache clean -> Suggest yarn cache clean when yarn [install] was run hadolint/hadolint#395
• Change ADD with COPY since you do not copy any *.tar files -> nr 7
• Add --no-install-recommends

[codecov]

Codecov Report

Merging #9081 (bcdd8bd) into master (2e0b2a1) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #9081      +/-   ##
==========================================
- Coverage   45.48%   45.44%   -0.05%     
==========================================
  Files         217      217              
  Lines       25655    25655              
==========================================
- Hits        11669    11658      -11     
- Misses      12357    12371      +14     
+ Partials     1629     1626       -3     

Impacted Files	Coverage Δ
applicationset/services/scm_provider/github.go	63.52% <0.00%> (-17.65%)	⬇️
util/settings/settings.go	48.10% <0.00%> (ø)
applicationset/services/scm_provider/utils.go	88.50% <0.00%> (+4.59%)	⬆️

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[crenshaw-dev]

One clarifying question. Otherwise lgtm!

[pasha-codefresh]

LGTM, thank you!