…#26383)

We are seeing the following sorts of errors in production, as reported
by sentry, in v12.0.2:
`No metadata found for 'conversionDate'`
`No metadata found for 'usdConversionRate'`
`No metadata found for 'nativeCurrency'`
`No metadata found for 'conversionRate'`

Example issue:
https://metamask.sentry.io/issues/5682684113/events/b8006eebb65749f883e907242e52215b/?project=273505&query=is%3Aunresolved+issue.priority%3A%5Bhigh%2C+medium%5D+No+metadata+release%3A12.0.1&referrer=previous-event&statsPeriod=14d&stream_index=1

The `CurrencyRateController` stopped using six such properties with
MetaMask/core#1805, which was brought into the
extension with #21549, however, there was not a state migration to
delete those properties at the time

This PR adds migrations to delete those obsolete properties

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Fixes: #26356

To observe the error using steps that mimic users in production
1. Install v11.6.0 and onboard
2. Create a local dev build from the `master` branch
3. Update the v11.6.0 install to the local dev build
4. See the errors in the service worker console

If you repeat those steps, but in step two build from this branch
instead of the `master` branch, the errors will not occur

For a faster manual test of this PR, create a local development build of
this branch and then run this script in the service worker console:
```
window.chrome.storage.local.get(({ data, meta }) => chrome.storage.local.set({ data: { ...data, CurrencyController: { ...data.CurrencyController, conversionDate: 'Jan 1', conversionRate: '2', nativeCurrency: 'test' } }, meta: {...meta, version: 120 } }, () => { chrome.runtime.reload() }))
```
There should be no errors like `No metadata found for 'conversionRate'`
(but if you do the same on develop or master, those errors should be
present)

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Not required for external contributors.

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
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---------

Co-authored-by: Mark Stacey <markjstacey@gmail.com>