Prevent error when index doesn't exist
Prevent error when index doesn't exist

**Purpose**

PR #8882 introduced a bug where an uncaught `NotFoundError` would
be raised if `_get_relevant_indices` returned any indices that
don't exist in ES

**Changes**

Fall back to an unoptimized query if a `NotFoundError` is raised
during search.

**QA Notes**

Will self-QA this fix

**Ticket**

https://openscience.atlassian.net/browse/PLAT-1291

brianjgeiger/osf.io,cslzchen/osf.io,brianjgeiger/osf.io,felliott/osf.io,adlius/osf.io,cslzchen/osf.io,adlius/osf.io,brianjgeiger/osf.io,Johnetordoff/osf.io,pattisdr/osf.io,baylee-d/osf.io,cslzchen/osf.io,CenterForOpenScience/osf.io,mfraezz/osf.io,adlius/osf.io,pattisdr/osf.io,CenterForOpenScience/osf.io,CenterForOpenScience/osf.io,mattclark/osf.io,aaxelb/osf.io,saradbowman/osf.io,Johnetordoff/osf.io,aaxelb/osf.io,felliott/osf.io,cslzchen/osf.io,baylee-d/osf.io,Johnetordoff/osf.io,adlius/osf.io,aaxelb/osf.io,aaxelb/osf.io,mfraezz/osf.io,Johnetordoff/osf.io,mattclark/osf.io,felliott/osf.io,mfraezz/osf.io,CenterForOpenScience/osf.io,mfraezz/osf.io,baylee-d/osf.io,saradbowman/osf.io,brianjgeiger/osf.io,felliott/osf.io,pattisdr/osf.io,mattclark/osf.io