Revert `execute_blob` and `send_blob` (#4266)

Revert "pallet-xcm: Deprecate `execute` and `send` in favor of
`execute_blob` and `send_blob` (#3749)"

This reverts commit feee773d

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Co-authored-by: Adrian Catangiu <[email protected]>
Co-authored-by: Javier Bullrich <[email protected]>