chore: Use network-specific smart transaction feature flags

[dan437]

Description

If there are network-specific feature flags for smart transactions, they will take priority over shared smart transaction feature flags.

Related issues

Fixes:

Manual testing steps

1. Turn off some feature flag which is network-specific for smart transactions (e.g. bsc.smartTransactions.extensionActive = false)
2. See that it's being used over a shared one (smartTransactions.extensionActive)

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[metamaskbot]

Builds ready [146fd62]

• builds: chrome, firefox
• builds (flask): chrome, firefox
• builds (MMI): chrome
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7
  • common: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
  • content-script: 0
  • offscreen: 0

Page Load Metrics (1669 ± 44 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	1520	1847	1666	90	43
		domContentLoaded	1512	1834	1639	86	41
		load	1521	1845	1669	92	44
		domInteractive	23	74	37	16	8
		backgroundConnect	9	79	34	24	11
		firstReactRender	15	70	34	22	10
		getState	4	38	10	7	3
		initialActions	0	1	0	0	0
		loadScripts	1042	1346	1195	76	36
		setupStore	6	56	16	16	8
		uiStartup	1732	2121	1900	113	54

Bundle size diffs [🚨 Warning! Bundle size has increased!]

• background: 0 Bytes (0.00%)
• ui: 0 Bytes (0.00%)
• common: 63 Bytes (0.00%)