random tests failures that might hint to bugs

[individual-it]

API tests sometimes fail with weird errors that hint to bugs in ocis, but they are hard to catch because the tests only fail randomly.
This issue is an overview of sub-issues that contain the details:

• Downloading file preview can sometimes fail with 500 error (oCIS Fix: fix: request to preview gives 500 error for old/new webdav if file is in processing #7507)
• PROPFIND to old share name after renaming by sharee gives 207 with old item in response (oCIS FIx: Reuse existing mountpoints on auto accept #7592)
• Flaky API tests due to index is closed error in search service (oCIS Fix: Init search service correctly #7795)
• Sharing steps sometimes fail with 998 response code (Test Fix: [tests-only] Fix share creation methods #7400)
• API test failing with Syntax error (JsonException) (Test Fix: [tests-only] Retry listing roles if the response body is invalid #7735)
• Upload / download file steps sometimes fail with 404 statuscode
• Sometimes API test steps fail with space not found error (Test fix: [tests-only] Retry space listing if required space is not found #7521)

[individual-it]

ToDo QA-team: check if the list is still useful, and close if not

[nirajacharya2]

Most of the sub-issues mentioned in this issues have a merged fix PR which solved the issue except for #7337.

Checked the builds from last 10 days. I didn't see any failed steps mentioned in #7337. I think this issue should be closed.

CC @saw-jan @amrita-shrestha @individual-it @Salipa-Gurung