Fix updateCaveat not being exposed in the background API

[FrederikBolding]

Description

Follow up to #20983

Fixes an issue where updateCaveat was not being exposed in the background API. This caused problems when trying to disconnect a single dapp from a snap. I had misdiagnosed the bug in the first PR and thought that it was fixed, but @NidhiKJha reported that it was still broken.

Manual testing steps

1. Connect to 2 snaps from a single dapp
2. Go to one of the snap's settings
3. Disconnect from the dapp
4. Go to the other snap's settings and check that you are not disconnected

[NidhiKJha]

LGTM

[metamaskbot]

Builds ready [5d1857d]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4
  • common: 0, 1, 2, 3, 4, 5, 6
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1700 ± 81 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	133	177	154	13	6
		domContentLoaded	1526	2274	1699	169	81
		load	1526	2274	1700	169	81
		domInteractive	1526	2274	1699	169	81

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

• background: 42 Bytes (0.00%)
• ui: -403 Bytes (-0.00%)
• common: 0 Bytes (0.00%)

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.02% ⚠️

Comparison is base (452e177) 68.41% compared to head (5d1857d) 68.40%.
Report is 2 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #20986      +/-   ##
===========================================
- Coverage    68.41%   68.40%   -0.02%     
===========================================
  Files         1006     1006              
  Lines        40205    40187      -18     
  Branches     10752    10743       -9     
===========================================
- Hits         27506    27487      -19     
- Misses       12699    12700       +1     

Files Changed	Coverage Δ
app/scripts/metamask-controller.js	53.80% <0.00%> (-0.14%)	⬇️

... and 5 files with indirect coverage changes

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