PDF_Filler temp files need to be unique

[cloudmagic80]

"Due to the growing number of 7959F1 files, our temporary files with the same name can cause conflicts. This could lead to issues if two users try to save a file with the same 7959F1 name simultaneously."
If the files are named correctly, we won't see this error:Error: An error occurred while verifying stamp: No such file or directory @ rb_file_s_rename which is caused by conflicting naming, e.g. tmp/vha_10_7959f_1-stamped.pdf or tmp/vha_10_7959f_1.pdf

Old AC: Each application 7959F1 file unique name, like use a SecureRandom.hex. example:
generated_form_path = Rails.root.join("tmp/#{name}-#{SecureRandom.hex}-tmp.pdf").to_s
stamped_template_path = Rails.root.join("tmp/#{name}-#{SecureRandom.hex}-stamped.pdf").to_s

New AC:
All temporary files must be uniquely named.
Need unit test to ensure that the output file for s3 is named correctly:
It should not be this format: tmp/vha_10_7959f_1-cf1b6e07204447096d9bf37837c61df7.pdf
or thistmp/vha_10_7959f_1-stamped.pdfor tmp/vha_10_7959f_1.pdf
Correct format is: tmp/0099687f-7e9c-45a9-8865-ac67f0d7ef31_vha_10_7959f_1.pdf for PEGA to process the claims

[cloudmagic80]

https://github.com/department-of-veterans-affairs/vets-api/pull/19060/files

[cloudmagic80]

Reverting the PR.

[cloudmagic80]

department-of-veterans-affairs/vets-api#19118

[cloudmagic80]

This new PR: https://github.com/department-of-veterans-affairs/vets-api/pull/19143/files
supersedes the other PRs that came before this one

[cloudmagic80]

LGTM @stevelong00

[stevelong00]

The PR has all needed approvals and is ready to merge. @baltes, shall I proceed with the merge?

[baltes]

@stevelong00 If it's behind a feature flag, we can merge. If not, we probably need testing steps to verify it in staging before it goes to prod.

[stevelong00]

@baltes It's behind a feature flag and currently disabled in all environments. Merging now.

[cloudmagic80]

@baltes This looks good in staging.