[10.2.0] Filter unavailable users and remove unavailable shares on polling

[VicDeo]

Backport of #35010

Description

Protect polling from exploding on unavailable users

Motivation and Context

An unhandled exception has been thrown: TypeError: Argument 1 passed to OCA\Files_Sharing\External\MountProvider::getMountsForUser() must implement interface OCP\IUser, null given, when UserManager knows nothing about a userId

How Has This Been Tested?

1. Create and accept a federated share
2. Execute update oc_share_external set user="Iwouldliketobreakthepolling" limit 1;

Expected

Polling goes through all entries with no termination

Actual

Polling terminates with TypeError: Argument 1 passed to OCA\Files_Sharing\External\MountProvider::getMountsForUser() must implement interface OCP\IUser, null given

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Database schema changes (next release will require increase of minor version instead of patch)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:

[PVince81]

@individual-it can you check the error in https://drone.owncloud.com/owncloud/core/16933/903 ? it's not related but suspicious nonetheless.

[individual-it]

WebDriver\Exception\JavaScriptError: ReferenceError: jQuery is not defined

I guess the problem is that we try to run some JS script from the acceptance tests before FF has loaded and run all jQuery files

[PVince81]

restarted failed build

[individual-it]

build was cancelled, probably because of some drone issue, several job run for more than 2h. restarted

[codecov]

Codecov Report

Merging #35073 into release-10.2.0 will increase coverage by <.01%.
The diff coverage is 79.31%.

@@                 Coverage Diff                  @@
##             release-10.2.0   #35073      +/-   ##
====================================================
+ Coverage             64.29%   64.29%   +<.01%     
- Complexity            20040    20044       +4     
====================================================
  Files                  1285     1285              
  Lines                 76824    76846      +22     
  Branches               1307     1307              
====================================================
+ Hits                  49394    49410      +16     
- Misses                27049    27055       +6     
  Partials                381      381

Flag	Coverage Δ	Complexity Δ
#javascript	53.01% <ø> (ø)	0 <ø> (ø)	⬇️
#phpunit	65.49% <79.31%> (ø)	20044 <3> (+4)	⬆️

Impacted Files	Coverage Δ	Complexity Δ
...s/federatedfilesharing/lib/AppInfo/Application.php	45.89% <0%> (-0.97%)	19 <0> (ø)
...atedfilesharing/lib/Command/PollIncomingShares.php	98.52% <100%> (+0.41%)	13 <2> (+2)	⬆️
apps/files_sharing/lib/External/Manager.php	77.38% <40%> (-1.28%)	32 <1> (+2)

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