Improve logic of finding legacy branches to ignore manifest update

[peterzhuamazon]

Description

Improve logic of finding legacy branches to ignore manifest update
Using legacy-manifests folder as indicator of legacy branch and cross checking with current manifests.

Issues Resolved

Follow up to: #4867
Closes #4870

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[peterzhuamazon]

Results:

2024-07-19 18:44:24 INFO     Known versions: ['1.0.0', '1.0.1', '1.1.0', '1.1.1', '1.2.0', '1.2.1', '1.2.2', '1.2.3', '1.2.4', '1.2.5', '1.3.0', '1.3.1', '1.3.2', '1.3.3', '1.3.4', '1.3.5', '1.3.6', '1.3.7', '1.3.8', '1.3.9', '1.3.10', '1.3.11', '1.3.12', '1.3.13', '1.3.14', '1.3.15', '1.3.16', '1.3.17', '1.3.18', '1.4.0', '2.0.0', '2.0.1', '2.0.2', '2.1.0', '2.1.1', '2.2.0', '2.2.1', '2.2.2', '2.3.0', '2.3.1', '2.4.0', '2.4.1', '2.4.2', '2.5.0', '2.5.1', '2.6.0', '2.6.1', '2.7.0', '2.7.1', '2.8.0', '2.8.1', '2.9.0', '2.9.1', '2.10.0', '2.10.1', '2.11.0', '2.11.1', '2.11.2', '2.12.0', '2.12.1', '2.13.0', '2.13.1', '2.14.0', '2.14.1', '2.15.0', '2.15.1', '2.16.0', '3.0.0']
2024-07-19 18:44:24 INFO     Checking out components into /var/folders/3m/3z1h4cv934z_dxprx6ygmm6w0000gq/T/tmp14gz0ia_
2024-07-19 18:44:25 INFO     Checking OpenSearch ['1.3', '1.x', '2.12', '2.13', '2.14', '2.15', '2.x', 'main'] branches
2024-07-19 18:44:25 INFO     Ignoring OpenSearch ['1.0', '1.1', '1.2', '2.0', '2.1', '2.10', '2.11', '2.2', '2.3', '2.4', '2.5', '2.5-transfer', '2.6', '2.7', '2.8', '2.9'] branches as they are outdated
2024-07-19 18:44:25 INFO     Executing "git init" in /var/folders/3m/3z1h4cv934z_dxprx6ygmm6w0000gq/T/tmp14gz0ia_/OpenSearch/1.3
2024-07-19 18:44:25 INFO     Executing "git remote add origin https://github.com/opensearch-project/OpenSearch.git" in /var/folders/3m/3z1h4cv934z_dxprx6ygmm6w0000gq/T/tmp14gz0ia_/OpenSearch/1.3
2024-07-19 18:44:25 INFO     Executing "git fetch --depth 1 origin 1.3" in /var/folders/3m/3z1h4cv934z_dxprx6ygmm6w0000gq/T/tmp14gz0ia_/OpenSearch/1.3