[github] Fix get_identities method not returning all identities

[jjmerchante]

This PR fixes a bug that cause that some identities were not loaded in SortingHat and in OpenSearch were displayed as UNDEFINED.

The method get_identities was not returning the identities from reviews_data.

[coveralls]

Pull Request Test Coverage Report for Build 6416571174

• 14 of 14 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.006%) to 85.546%

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Totals
Change from base Build 6404879552:	0.006%
Covered Lines:	7487
Relevant Lines:	8752

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💛 - Coveralls