Separate directory creation concern from `GetAbsRemoteUrl`

[elianddb]

The getAbsFileRemoteUrl function in remotes.go creates missing directories when processing file:// remote URLs. This side-effect is inappropriate for a URL normalization function. Removing this behavior breaks multiple tests that depend on the implicit directory creation, including clone operations, fetch operations, and remote management commands.

not ok 145 auto_increment: newly cloned database
not ok 378 clone-drop: clone a database and then drop it
not ok 378 clone-drop: sql-server: clone a database and then drop it
not ok 908 fetch: fetch --prune deletes remote refs not on remote
not ok 913 fetch: fetching from empty remote
not ok 1751 merge: setting DOLT_AUTHOR_DATE and DOLT_COMMITTER_DATE
not ok 1856 nonlocal: remote ref
not ok 2041 remotes-file-system: Add a file system remote with a bad path
not ok 2081 remotes-push-pull: pull with DOLT_AUTHOR_DATE and DOLT_COMMITER_DATE doesn't overwrite commit timestamps
not ok 2168 remotes: fetch --prune deletes remote refs not on remote
not ok 2236 replication: commit --amend
not ok 2334 shallow-clone: shallow clone with a file path
not ok 2335 shallow-clone: fast forward merge
not ok 2335 shallow-clone: simple merge
not ok 2335 shallow-clone: no-op merge
not ok 2335 shallow-clone: push to a new remote should error
not ok 2604 sql-fetch: fetch --prune deletes remote refs not on remote
TestDoltCheckout
TestDoltCheckoutPrepared

Directory creation should be handled explicitly by callers or through a separate function. For example, dolt_backup.go currently relies on PrepareDB to create directories for file:// URLs (pr).