chore: Remove L2CM and CANNON_KONA Dev Feature Flags

[0xCoati]

Removes the L2CM and CannonKona dev feature flags, making both the default codepath.

L2CM:

• Drops the flag constant and its hardcoded short-circuit from both the Solidity (DevFeatures.sol) and Go (devfeatures.go) definitions.
• Makes the ConditionalDeployer and L2DevFeatureFlags predeploys unconditional in the Predeploys registry.
• Cleans up tests and removes redundant test-cases.

CannonKona:

• Drops the flag constant and short-circuit the same way (bit 0x10 retired).
• Collapses the only production branch — the startingRespectedGameType override gate in OPContractsManagerV2._isPermittedInstruction — to the always-on path (behavior-neutral, the shim already forced it to true).
• Removes the DEV_FEATURE__CANNON_KONA env plumbing (Config.sol, FeatureFlags.sol), the *AlwaysEnabled* override tests, fuzz-test exclusions, and the commented-out CI matrix entry.
• Bumps OPContractsManagerV2 7.1.23 → 7.1.24; regenerates semver-lock.json and the NUT bundle snapshot.

Note: on-chain L2DevFeatureFlags.isDevFeatureEnabled(0x10) now reports the actual bitmap instead of always-true — same precedent as the retired L2CM bit; nothing on-chain consumes it.

Notes

Addresses both flag removals from #20084 . The removal of the entire dev features system should be tracked in a separate issue.