fix: hide network picker back button when network is unselected

[micaelae]

Description

Related issues

Fixes: https://consensyssoftware.atlassian.net/browse/MMS-1852

Manual testing steps

1. Go to this page...

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.

[metamaskbot]

Builds ready [d1b7579]

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

Page Load Metrics (1513 ± 44 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	1385	1689	1515	91	44
		domContentLoaded	1378	1674	1490	88	42
		load	1387	1687	1513	91	44
		domInteractive	23	90	38	19	9
		backgroundConnect	5	83	23	22	10
		firstReactRender	15	102	57	30	14
		getState	5	81	17	23	11
		initialActions	0	1	0	0	0
		loadScripts	993	1297	1111	83	40
		setupStore	5	86	10	17	8
		uiStartup	1550	2280	1847	205	98

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 12 Bytes (0.00%)
• common: 0 Bytes (0.00%)