[FLASK] Remove Snaps execution environment override

[Mrtenz]

Explanation

This removes the createSnapExecutionService option, as this was never used. If this becomes necessary in the future, a better approach would be to use build flags, to only include the execution environment we need.

Pre-merge author checklist

• I've clearly explained:
  • What problem this PR is solving
  • How this problem was solved
  • How reviewers can test my changes
• Sufficient automated test coverage has been added

Pre-merge reviewer checklist

• Manual testing (e.g. pull and build branch, run in browser, test code being changed)
• PR is linked to the appropriate GitHub issue
• IF this PR fixes a bug in the release milestone, add this PR to the release milestone

[metamaskbot]

Builds ready [80e4fb2]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): 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, 5
  • common: 0, 1, 2, 3, 4, 5
  • 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 (1782 ± 73 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	103	249	155	38	18
		domContentLoaded	1492	2112	1781	152	73
		load	1492	2112	1782	152	73
		domInteractive	1492	2112	1781	152	73

Bundle size diffs

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

[codecov]

Codecov Report

Merging #20173 (80e4fb2) into develop (fdc3558) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop   #20173   +/-   ##
========================================
  Coverage    69.42%   69.42%           
========================================
  Files          985      985           
  Lines        37294    37294           
  Branches     10012    10011    -1     
========================================
  Hits         25889    25889           
  Misses       11405    11405           

Files Changed	Coverage Δ
app/scripts/metamask-controller.js	65.43% <ø> (ø)