Do not create the default folders for DirectoryStore on Open

[mregen]

Proposed changes

For convenience, the DirectoryStore class creates the default folders when the DirectoryStore is opened. (since #2720)
However this may lead into issues mapping folders to the store when started in docker.

Fix: remove the code which creates default folders and ensure a null directory does not throw a NullReferenceException.

Related Issues

• Fixes AddRejected method for ICertificateStore #2720

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[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 54.72%. Comparing base (5349d9a) to head (8da3156).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
...Security/Certificates/DirectoryCertificateStore.cs	33.33%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2773      +/-   ##
==========================================
+ Coverage   54.62%   54.72%   +0.09%     
==========================================
  Files         349      349              
  Lines       65705    65691      -14     
  Branches    13446    13442       -4     
==========================================
+ Hits        35889    35947      +58     
+ Misses      25923    25861      -62     
+ Partials     3893     3883      -10     

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[ThomasNehring]

Another, seemingly new place where a directory is newly created is in the load(thumbprint) method. Are we sure this is not also causing an issue? Why do we create a store when we want to read the certificates from that store? If it does not exist, the list of certificates is obviously empty. Also, in this case, we do not catch an exception if creating the subdirectory fails.

(If that's not an issue I can approve if you want)

[mregen]

@ThomasNehring I removed the other create and added some more sanity check for null, just to be safe