fix: fetch quotes when dest asset is native

[micaelae]

Description

This fixes the bug in which quotes are not fetched when the destination is a native asset. This was due to the token address being empty, which was causing validation to fail

Related issues

Fixes: https://consensyssoftware.atlassian.net/browse/MMS-2033

Manual testing steps

1. Go to Bridge page (EVM or solana)
2. Select native asset for both src and dest
3. Quotes should be fetched

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 [e63723c]

• 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, 8
  • 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 (1703 ± 49 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	505	1956	1648	282	135
		domContentLoaded	1487	1908	1678	100	48
		load	1533	1957	1703	103	49
		domInteractive	26	91	45	19	9
		backgroundConnect	9	58	27	18	8
		firstReactRender	14	74	41	25	12
		getState	5	54	9	10	5
		initialActions	0	1	0	0	0
		loadScripts	1099	1511	1253	99	47
		setupStore	8	66	21	21	10
		uiStartup	1749	2186	1958	104	50

Bundle size diffs [🚀 Bundle size reduced!]

• background: 0 Bytes (0.00%)
• ui: 156 Bytes (0.00%)
• common: -52 Bytes (-0.00%)