bootstrap.sh improvements

[nirbosl]

Description:

• Simplified process tracking by removing the processing_files associative array and relying on the pids array for job tracking
• Fixed an issue where all child processes would print out the same PID as theirs, which was in fact the script parent-group-ID; each process now properly prints its own job PID, also resulting in PGAPPNAME reflecting the correct PID in the DB COPY jobs.
• Extended the validate_special_files function with additional validation logic
  • Fixes an issue of an error thrown for special files validation when re-running the script
• Improved robustness of file validation checks
• Enhanced the import_file function with additional error handling and verification steps
• Improved import reliability
• Improved code organization
• Maintained the same overall script structure and core functionality
• Converted DECOMPRESS_FLAGS into an array and added proper array handling for it; This allows to resolve a shellcheck/codacy smell regarding the var not being double-quoted to prevent globbing/splitting of the value.

Notes for reviewer:
The changes to the script's code are due to an issue a customer ran into. I was not able to reproduce the issue they ran into (valid file being imported but post-import row-count returns incorrectly then counts again and increments by the amount of rows it counts over and over).

I have focused on potential weaknesses I've identified that could potentially result in such edge-cases, and have refactored and improved their code to be more robust and safer in order to avoid such issues in the future.

I have repeat-tested the script using a dataset that included two large table file parts of each large table, and all small tables in the following two scnearios:

• Single run import with no interruptions (good path)
• Started an import, let it complete several files successfully then stop the script and re-run it (to validate resumption logic and proper skip of already-imported files)

All repeat tests in both scenarios finished successfully.

I have then started a local mirror-importer against the bootstrapped DB and it started cleanly and resumed sync from September 18th timestamps, which is the date this data export was taken on (0.113.2).

Checklist

• Documented (Code comments)
• Tested (Actual runs of the script, described above in the Notes section.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

see 165 files with indirect coverage changes

[jnels124]

LGTM