rpc: change default sorting to desc for /tx_search results

[melekes]

Closes #6155

[codecov]

Codecov Report

Merging #6168 (61d322c) into master (42f6c40) will decrease coverage by 0.06%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #6168      +/-   ##
==========================================
- Coverage   60.69%   60.63%   -0.07%     
==========================================
  Files         276      276              
  Lines       25706    25706              
==========================================
- Hits        15603    15586      -17     
- Misses       8482     8495      +13     
- Partials     1621     1625       +4     

Impacted Files	Coverage Δ
rpc/core/tx.go	0.00% <0.00%> (ø)
privval/signer_listener_endpoint.go	80.00% <0.00%> (-9.42%)	⬇️
mempool/reactor.go	65.71% <0.00%> (-5.00%)	⬇️
privval/socket_listeners.go	78.72% <0.00%> (-4.26%)	⬇️
privval/signer_endpoint.go	75.75% <0.00%> (-3.04%)	⬇️
privval/secret_connection.go	73.71% <0.00%> (-2.58%)	⬇️
consensus/reactor.go	67.24% <0.00%> (-2.36%)	⬇️
consensus/peer_state.go	78.94% <0.00%> (-0.88%)	⬇️
mempool/clist_mempool.go	80.21% <0.00%> (-0.72%)	⬇️
proxy/multi_app_conn.go	48.05% <0.00%> (ø)
... and 10 more

[cmwaters]

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