Convert transaction activity conversion's currency to ETH

[tmashuang]

Fixes #8933 where custom fromCurrency would crash the convertion utility and the UI.

This fixes in the mean time, but there still a separate issue with the nativeCurrency persisting in the background, it will reset to ETH upon background refresh.

See issue for before gif

Fix After Gif

[metamaskbot]

Builds ready [1d47396]

• builds: chrome, firefox, opera
• bundle viz: background, ui, inpage, contentscript, ui-libs, bg-libs, phishing-detect
• dep viz: background
• all artifacts

Page Load Metrics (979 ± 108 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	45	127	76	23	11
		domContentLoaded	473	1332	976	225	108
		load	475	1334	979	225	108
		domInteractive	472	1332	976	225	108

[Gudahtt]

LGTM!

I noticed we're passing in nativeCurrency as fromCurrency or toCurrency in other places as well, so similar bugs may still exist elsewhere.

[metamaskbot]

Builds ready [fdb1281]

• builds: chrome, firefox, opera
• bundle viz: background, ui, inpage, contentscript, ui-libs, bg-libs, phishing-detect
• dep viz: background
• all artifacts

Page Load Metrics (589 ± 51 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	29	79	39	16	8
		domContentLoaded	340	685	588	106	51
		load	341	686	589	106	51
		domInteractive	339	685	587	106	51