[#768] Added checking for bin existence in scripts.

[tannguyen04]

Checklist before requesting a review

closes #768

• I have formatted the subject to include ticket number as [#123] Verb in past tense with dot at the end.
• I have added a link to the issue tracker
• I have provided information in Changed section about WHY something was done if this was not a normal implementation
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have run new and existing relevant tests locally with my changes, and they passed
• I have provided screenshots, where applicable

Changed

Screenshots

[codecov]

Codecov Report

Attention: Patch coverage is 14.58333% with 82 lines in your changes are missing coverage. Please review.

Project coverage is 66.76%. Comparing base (3a97f9f) to head (e1a6b60).

Files	Patch %	Lines
scripts/drevops/download-db-acquia.sh	0.00%	4 Missing ⚠️
scripts/drevops/download-db-docker-registry.sh	0.00%	4 Missing ⚠️
scripts/drevops/download-db-ftp.sh	0.00%	4 Missing ⚠️
scripts/drevops/download-db-lagoon.sh	0.00%	4 Missing ⚠️
scripts/drevops/login-docker.sh	0.00%	4 Missing ⚠️
scripts/drevops/mirror-code.sh	0.00%	4 Missing ⚠️
scripts/drevops/task-copy-db-acquia.sh	0.00%	4 Missing ⚠️
scripts/drevops/task-copy-files-acquia.sh	0.00%	4 Missing ⚠️
scripts/drevops/task-custom-lagoon.sh	0.00%	4 Missing ⚠️
scripts/drevops/task-purge-cache-acquia.sh	0.00%	4 Missing ⚠️
... and 14 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1271      +/-   ##
===========================================
- Coverage    68.35%   66.76%   -1.60%     
===========================================
  Files           50       50              
  Lines         3087     3177      +90     
===========================================
+ Hits          2110     2121      +11     
- Misses         977     1056      +79     

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