Ensure solana_provider_ is connected before checking IsSolanaKeyringCreated

[darkdh]

Resolves brave/brave-browser#28147

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally:
  • npm run test -- brave_browser_tests, npm run test -- brave_unit_tests wiki
  • npm run lint, npm run presubmit wiki, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

STR in the issue

[kjozwiak]

Verification PASSED on Win 11 x64 using the following build(s):

Brave | 1.49.78 Chromium: 110.0.5481.52 (Official Build) nightly (64-bit)
-- | --
Revision | 979113183ded4544a2c443aceb1629c430907e52-refs/branch-heads/5481@{#636}
OS | Windows 11 Version 22H2 (Build 22621.1105)

Using the STR/Cases outlined via brave/brave-browser#28147 (comment), ensured that Brave wasn't crashing when visiting the following websites:

• https://www.youtube.com
• https://www.reddit.com
• https://diablo2.io/base/#filter=
• https://traderie.com/diablo2resurrected?prop_Platform=PC&prop_Ladder=true
• https://steamdb.info
• https://etherscan.io

Also ensured that opening the wallet via the Brave Wallet panel didn't cause the browser to crash as it did before.

---

Verification PASSED on Pixel 6 running Android 13 using the following build(s):

Brave | 1.49.79 Chromium: 110.0.5481.52 (Official Build) canary (32-bit)
--- | ---
Revision | 979113183ded4544a2c443aceb1629c430907e52-refs/branch-heads/5481@{#636}
OS | Android 13; Build/TQ1A.230105.002

Using the STR/Cases outlined via brave/brave-browser#28147 (comment), ensured that Brave wasn't crashing when visiting the following websites:

• https://www.youtube.com
• https://www.reddit.com
• https://diablo2.io/base/#filter=
• https://traderie.com/diablo2resurrected?prop_Platform=PC&prop_Ladder=true
• https://steamdb.info
• https://etherscan.io

Also ensured that opening Wallet from the Hamburger Menu didn't cause any issues/crashes.