Describe upgrade process without gateway

[StanislavBreadless]

What ❔

Why ❔

Checklist

• PR title corresponds to the body of PR (we generate changelog entries from PRs).
• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.

[github-actions]

Coverage after merging sb-upgrade-process-no-gateway into release-v26 will be

83.73%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
contracts/bridge
BridgeHelper.sol	76%	40%	100%	84.21%	29, 31, 34, 36, 39, 41
BridgedStandardERC20.sol	74.68%	25%	92.31%	77.59%	120–121, 126–127, 139–140, 163–164, 205, 205, 212, 212, 219, 219, 230, 62–63, 90–91
L1ERC20Bridge.sol	89.58%	66.67%	100%	91.43%	188–189, 207–208, 269
L1Nullifier.sol	77.97%	54.76%	86.21%	82.69%	115–116, 131, 131–132, 161–162, 222–223, 225–226, 235–236, 238–239, 248–249, 251–252, 418, 420–421, 421–422, 425–426, 426–427, 453–454, 519–520, 611–612, 649–652, 708, 711, 713, 726, 740, 745, 764–765
contracts/bridge/asset-router
AssetRouterBase.sol	90.24%	60%	100%	92.86%	58–59, 86–87
L1AssetRouter.sol	84.66%	62.50%	88.89%	89.23%	208–209, 245–247, 258, 260, 263, 361, 391–392, 435–437, 450–451, 553–554, 59–60, 654, 673, 75–76, 83–84
contracts/bridge/interfaces
AssetHandlerModifiers.sol	50%	0%	100%	50%	12–13
contracts/bridge/ntv
L1NativeTokenVault.sol	79.34%	62.07%	87.50%	84.21%	141, 144–145, 145, 145–147, 147, 147–149, 149, 149–150, 152, 207, 218, 220, 220, 220–221, 223, 236
NativeTokenVault.sol	83.87%	59.38%	92%	88.37%	101–102, 230–231, 235–236, 252–253, 270–271, 275–276, 290, 292, 310–311, 318–319, 483, 485, 499–500, 527–528, 562, 567, 73–74
contracts/bridgehub
Bridgehub.sol	77.65%	39.29%	93.18%	83.75%	115–116, 123–124, 130–131, 137, 137–138, 167, 182–183, 227–228, 230–231, 239–240, 249–250, 262–263, 277–278, 306–307, 330–331, 333–334, 399–400, 415–416, 446–447, 526–527, 608–609, 717–718, 722–723, 725–726, 730, 730–731, 735–736, 738–739, 778–779, 781–782, 796–797, 842–843, 845–846, 848–849, 883–884, 887–888, 890–891, 926, 931
CTMDeploymentTracker.sol	62.79%	0%	90%	69.23%	122–123, 128, 31–32, 39–40, 62–63, 89–90, 93–94, 97–98
MessageRoot.sol	88.89%	40%	100%	91.89%	121–122, 67–68, 88–89
contracts/common
ReentrancyGuard.sol	90%	66.67%	100%	92.86%	78–79
contracts/common/libraries
DataEncoding.sol	78.26%	50%	100%	81.48%	110, 118, 143, 156, 163, 172, 174, 177, 43, 45
DynamicIncrementalMerkle.sol	74.42%	100%	80%	72.22%	67–70, 72–74, 76–78
FullMerkle.sol	100%	100%	100%	100%
L2ContractHelper.sol	58.49%	0%	75%	67.57%	100–101, 106–107, 110–111, 125, 127, 127–128, 132, 132–133, 141, 71–72, 77–78, 81–82
Merkle.sol	96.43%	85.71%	100%	97.73%	81–82
MessageHashing.sol	100%	100%	100%	100%
SemVer.sol	100%	100%	100%	100%
SystemContractsCaller.sol	0%	0%	0%	0%	114, 122–125, 135–138, 138–139, 141, 141–142, 33, 33–34, 37, 45, 47, 49, 51, 53, 66, 66, 66, 69, 72, 75, 78, 89, 91, 93, 96, 98
UncheckedMath.sol	100%	100%	100%	100%
UnsafeBytes.sol	100%	100%	100%	100%
contracts/governance
AccessControlRestriction.sol	100%	100%	100%	100%
ChainAdmin.sol	95.24%	80%	100%	96.30%	38–39
ChainAdminOwnable.sol	39.29%	0%	40%	47.37%	27–28, 39–40, 47–48, 56–57, 63, 66, 78, 78–79, 81
Governance.sol	98.15%	94.74%	100%	98.55%	45–46
L2ProxyAdminDeployer.sol	0%	100%	0%	0%	17–18, 20
PermanentRestriction.sol	83.45%	67.86%	100%	85.57%	103–104, 111, 111–112, 200, 200–201, 204, 204–205, 208, 210, 210–211, 240, 242, 289–290, 311–312, 342–343
TransitionaryOwner.sol	0%	100%	0%	0%	17, 22–23
contracts/governance/restriction
Restriction.sol	100%	100%	100%	100%
RestrictionValidator.sol	100%	100%	100%	100%
contracts/state-transition
ChainTypeManager.sol	72.12%	22.22%	71.43%	80.36%	147–148, 150–151, 153–154, 156–157, 212–213, 243–244, 268, 292, 311, 318, 325, 333, 340, 348, 355, 371, 373, 434–435, 462–463, 469–470, 496–497, 544–545, 79, 94–95
TestnetVerifier.sol	77.78%	66.67%	100%	75%	16, 28
ValidatorTimelock.sol	92.06%	71.43%	100%	93.02%	186–187, 202, 78–79
Verifier.sol	89.90%	40%	96.30%	90.93%	1674–1675, 287–302, 305–308, 311–318, 321–328, 331–332, 335–336, 339, 383–384, 394–395, 405–406, 416–417, 427–428, 443–444, 453, 453–454, 905–906
contracts/state-transition/chain-deps
DiamondInit.sol	80.43%	50%	100%	88.24%	39–40, 42–43, 45–46, 48–49, 73
DiamondProxy.sol	92.31%	75%	100%	100%	19, 30
GatewayCTMDeployer.sol	0%	0%	0%	0%	156, 161–163, 165, 167, 169, 177, 179–180, 182–183, 185, 205, 208–209, 211, 217, 221–222, 235, 235, 235–236, 238, 255, 257, 259–260, 264, 266–268, 281, 284–286, 288–289, 295, 301, 307, 314, 324, 330, 332, 342, 349,