roachtest: restrict rebalance/by-load/*/mixed-version to v25.1+

There have been many performance improvements in versions 25.1.0+. In
particular, the CPU utilization attributed to SQL can vary
significantly between versions, which can lead to flakiness in these
tests since the StoreRebalancer, which operates at the store level, is
unaware of such CPU use.

Fixes: #150603

Release note: None

Author: miraradeva

pkg/cmd/roachtest/tests/rebalance_load.go

@@ -110,7 +110,12 @@ func registerRebalanceLoad(r registry.Registry) {
 				),
 				// Only use the latest version of each release to work around #127029.
 				mixedversion.AlwaysUseLatestPredecessors,
-				mixedversion.MinimumSupportedVersion("v23.2.0"),
+				// There have been many performance improvements in versions 25.1.0+.
+				// In particular, the CPU utilization attributed to SQL can vary
+				// significantly between versions, which can lead to flakiness in these
+				// tests since the StoreRebalancer, which operates at the store level,
+				// is unaware of such CPU use (e.g. #150603).
+				mixedversion.MinimumSupportedVersion("v25.1.0"),
 			)
 			mvt.OnStartup("maybe enable split/scatter on tenant",
 				func(ctx context.Context, l *logger.Logger, r *rand.Rand, h *mixedversion.Helper) error {