Possible document cache bug in apidom-ls

[frantuma]

see #3682

by @char0n :

Needed to fiddle with document URI to see the bug. Creating unique document uri made me see the bug and uncovered a hidden issue
if you just revert my change, you won't see the bug related to linting. It seems that using same document URI and just changing spec does have some side effects resulting in incorrect linting
whatever change is made in packages/apidom-ls/src/config/openapi/header/lint/allowed-fields-2-0.ts doesn't inflence the test, unless you make change I did in packages/apidom-ls/test/validate-valid.ts

Haven't manage to figure out why codespace setup did uncovered the bug and not the CI or local dev setup