UX Multichain: fixed padding for edit screen

[NidhiKJha]

This PR is to remove the extra margin between header and content from all the screens and just adding it to the send edit and swap screen.

• Fixes MetaMask/MetaMask-planning#850

Screenshots/Screencaps

Screen.Recording.2023-06-21.at.9.33.42.PM.mov

Manual Testing Steps

• Go to send and swap screen
• Check the content and header has gap of 16px

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

If further QA is required (e.g. new feature, complex testing steps, large refactor), add the Extension QA Board label.

In this case, a QA Engineer approval will be be required.

[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 [32a30ce]

• 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
  • 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 (1792 ± 83 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	99	177	143	21	10
		domContentLoaded	1569	2038	1772	160	77
		load	1569	2196	1792	172	83
		domInteractive	1569	2038	1772	160	77

Bundle size diffs

• background: 0 bytes
• ui: 6 bytes
• common: 0 bytes

[codecov]

Codecov Report

Merging #19707 (32a30ce) into develop (ed702af) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop   MetaMask/metamask-extension#19707   +/-   ##
========================================
  Coverage    70.79%   70.79%           
========================================
  Files          988      988           
  Lines        38366    38366           
  Branches     10042    10042           
========================================
  Hits         27161    27161           
  Misses       11205    11205           

Impacted Files	Coverage Δ
ui/pages/routes/routes.component.js	48.92% <ø> (-0.36%)	⬇️
ui/components/multichain/app-header/app-header.js	50.44% <100.00%> (+0.44%)	⬆️