fix unavailable download directory

[tzarebczan]

If an uploaded file had a directory that was removed, or if the old download directory doesn't exist, use the default.

PR Checklist

Please check all that apply to this PR using "x":

• I have checked that this PR is not a duplicate of an existing PR (open, closed or merged)
• I have checked that this PR does not introduce a breaking change
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PR Type

What kind of change does this PR introduce?

Why is this change necessary?

• Bugfix
• Feature
• Breaking changes (bugfix or feature that introduces breaking changes)
• Code style update (formatting)
• Refactoring (no functional changes)
• Documentation changes
• Other - Please describe:

Fixes

Issue Number: N/A

What is the current behavior?

What is the new behavior?

Other information

[codecov]

Codecov Report

Merging #1760 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1760      +/-   ##
==========================================
+ Coverage   63.82%   63.82%   +<.01%     
==========================================
  Files         150      150              
  Lines       13649    13652       +3     
==========================================
+ Hits         8711     8714       +3     
  Misses       4938     4938

Impacted Files	Coverage Δ
lbrynet/extras/daemon/Daemon.py	56.76% <100%> (+0.09%)	⬆️

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[tzarebczan]

@jackrobison said he'd take a shot at this in his branch.