Increase MovedFundsSweepLookBackBlocks from 30 to 50 days

A production failure left 363.54 BTC stuck because a
MovingFundsCompleted event was ~38 days old (273,886 blocks),
exceeding the 216,000-block (30-day) lookback. Bump the constant
to 360,000 blocks (~50 days) to provide 32% headroom beyond the
observed failure.

Author: lrsaturnino

pkg/tbtcpg/moved_funds_sweep.go

@@ -25,8 +25,8 @@ var ErrNoPendingMovedFundsSweepRequests = fmt.Errorf(
 
 // MovedFundsSweepLookBackBlocks is the look-back period in blocks used
 // when searching for submitted moving funds-related events. It's equal to
-// 30 days assuming 12 seconds per block.
-const MovedFundsSweepLookBackBlocks = uint64(216000)
+// 50 days assuming 12 seconds per block.
+const MovedFundsSweepLookBackBlocks = uint64(360000)
 
 // MovedFundsSweepTask is a task that may produce a moved funds sweep proposal.
 type MovedFundsSweepTask struct {