fix(docs): remove duplicate Mobula entry

[CryptAm]

• Removed the duplicated Mobula card from the Data & Indexing section.
• Verified against the official docs website (docs.abs.xyz/ecosystem/indexers), the duplication exists with identical cards and links.

[cursor]

PR Summary

Removes a duplicated Mobula card from the Data & Indexing page.

• Deduplicates Mobula entry in ecosystem/indexers.mdx CardGroup, leaving a single card/link.

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