Vstreamer: idempotent gtid set (bugfix)

[shlomi-noach]

Description

#18196 introduced a test flakiness that indicates a more serious problem: crashing vttablet due to

fatal error: concurrent map read and map write

goroutine 364949 gp=0x1400034dc00 m=17 mp=0x140008d4808 [running]:
runtime.fatal({0x1021f9923, 0x21})
	runtime/panic.go:1116 +0x48 fp=0x1400481adc0 sp=0x1400481ad90 pc=0x1000e5c58
internal/runtime/maps.fatal({0x1021f9923?, 0x1000ad1d0?})
	runtime/panic.go:1046 +0x20 fp=0x1400481ade0 sp=0x1400481adc0 pc=0x10011eb50
runtime.mapaccess2(0x1031abf00, 0x14000d81770, 0x1400481ae78)
	internal/runtime/maps/runtime_swiss.go:136 +0x48 fp=0x1400481ae50 sp=0x1400481ade0 pc=0x1000b04b8
vitess.io/vitess/go/mysql/replication.Mysql56GTIDSet.Contains(0x14000d81770, {0x1032e6b40?, 0x14002e9e750?})
	vitess.io/vitess/go/mysql/replication/mysql56_gtid_set.go:248 +0xc8 fp=0x1400481af00 sp=0x1400481ae50 pc=0x100bfd1f8
vitess.io/vitess/go/mysql/replication.Position.AtLeast(...)
	vitess.io/vitess/go/mysql/replication/replication_position.go:83
vitess.io/vitess/go/vt/vttablet/tabletserver/schema.(*Engine).ReloadAtEx(0x140006b3e10, {0x1032c7df8, 0x1053a98e0}, {{}, {0x1032e6b40?, 0x14002e9e750?}}, 0x0)
	vitess.io/vitess/go/vt/vttablet/tabletserver/schema/engine.go:405 +0x148 fp=0x1400481af90 sp=0x1400481af00 pc=0x1012d6ec8
vitess.io/vitess/go/vt/vttablet/tabletserver/schema.(*Engine).ReloadAt(...)
	vitess.io/vitess/go/vt/vttablet/tabletserver/schema/engine.go:389
vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer.(*vstreamer).parseEvent(0x14001dd8360, {0x1032fb590, 0x140020783a0}, 0x14004fa3630)
	vitess.io/vitess/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go:572 +0xbcc fp=0x1400481b330 sp=0x1400481af90 pc=0x1014b2f3c

After some investigation, it seems there's more concurrency at play than we'd like. For the time being, main is broken and we want to unbreak it. We thus revert the in-place GTID computation for now.

Related Issue(s)

#18196

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[vitess-bot]

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