Remove QueryTxsByTags or update to search with events.

[colin-axner]

Summary of Bug

Tags were removed in #4541. QueryTxsByTags is still used in the code to search with tags as shown here. This should either but removed or ideally rewritten to query by events.

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[fedekunze]

Do we need to get this for 0.37 ? @jackzampolin @alexanderbez ?

[alexanderbez]

Errrr the underlying Tendermint query functionality is identical. We should rename it to QueryTxsByEvents. But good catch nonetheless @colin-axner 👍