Remove leading zeros from DOI in rfc index files #11047

Description

ATM DOIs for older RFCs have leading zeros in rfc index files (rfc-index.txt, rfc-index.xml etc.)

These DOIs are still valid but there are alternative DOIs without leading zeros for these RFCS.
RFC index files should show the DOIs without leading zeros since systems have moved away from 4-digit RFC numbering.

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