Remove trailing slashes from Transaction Service URLs

[iamacook]

Summary

Resolves #1929

It is possible that Chain['transactionService' | 'vpcTransactionService'] have trailing slashes, which breaks requests to the Transaction Service as we expect none to be present.

This refines the incoming values, removing the trailing slash if present.

Changes

• Remove trailing slashes from Chain['transactionService' | 'vpcTransactionService'] if present
• Add appropriate test coverage

[coveralls]

Pull Request Test Coverage Report for Build 10898745054

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 90.658%

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Totals
Change from base Build 10879486809:	-0.02%
Covered Lines:	8354
Relevant Lines:	8840

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💛 - Coveralls

[PooyaRaki]

LGTM