Revert "feat(vscode): Prompt to get an access token when authentication fails"

Created by: rvantonder

Reverts sourcegraph/sourcegraph#40584.

Currently breaking build on ESLint failure: https://buildkite.com/sourcegraph/sourcegraph/builds/169299#0182d743-f9e3-4e42-8c39-dbd790596af7

/root/buildkite/build/sourcegraph/client/vscode/src/backend/instanceVersion.ts   | 41:9 error Promises must be awaited, end with a call to .catch, end with a call to .then with a rejection handler or be explicitly marked as ignored with the void operator @typescript-eslint/no-floating-promises   |     | /root/buildkite/build/sourcegraph/client/vscode/src/settings/accessTokenSetting.ts   | 4:1 error There should be at least one empty line between import groups import/order   | 4:1 error ./endpointSetting import should occur before import of ./readConfiguration import/order   | 5:1 error ../backend/instanceVersion import should occur before import of ./readConfiguration import/order   | 29:13 error Promises must be awaited, end with a call to .catch, end with a call to .then with a rejection handler or be explicitly marked as ignored with the void operator @typescript-eslint/no-floating-promises   | 34:13 error Promises must be awaited, end with a call to .catch, end with a call to .then with a rejection handler or be explicitly marked as ignored with the void operator @typescript-eslint/no-floating-promises   |     | ✖ 6 problems (6 errors, 0 warnings)   | 3 errors and 0 warnings potentially fixable with the --fix option.  

(Dunno why the lint didn't fire in the PR)

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.

Test plan

it's a revert