Fix corpus delete by updating corpus fetch

What does this MR do and why?

Fixes: #352073 (closed)

The bug

Deleting a corpus is done via the destroyPackage mutation. Deleting a corpus via the corpus management UI ends up with a corpus with missing data. See further below the issues that recently caused this bug. An MR landed ~4 days ago that seems to have caused this bug.

Describe in detail what your merge request does and why.

Screenshots or screen recordings

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How to set up and validate locally

1. Enable the feature flags: corpus_management and corpus_management_ui
2. Go to the security > configuration > corpus management (your_project_id/-/security/configuration/corpus_management)
3. Upload the corpus
4. delete the corpus.
5. The corpus should not be visible.

Database review:

Query before the changes:

AppSec::Fuzzing::Coverage::Corpus.joins(:package).where(package: { project_id: 29 }).explain
  AppSec::Fuzzing::Coverage::Corpus Load (0.6ms)  SELECT "coverage_fuzzing_corpuses".* FROM "coverage_fuzzing_corpuses" INNER JOIN "packages_packages" "package" ON "package"."id" = "coverage_fuzzing_corpuses"."package_id" WHERE "package"."project_id" = 29 /*application:console,db_config_name:main,line:(pry):7:in `__pry__'*/
=> EXPLAIN for: SELECT "coverage_fuzzing_corpuses".* FROM "coverage_fuzzing_corpuses" INNER JOIN "packages_packages" "package" ON "package"."id" = "coverage_fuzzing_corpuses"."package_id" WHERE "package"."project_id" = 29 /*application:console,db_config_name:main,line:(pry):7:in `__pry__'*/
                                                             QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------
 Nested Loop  (cost=0.15..4.18 rows=1 width=56)
   ->  Seq Scan on coverage_fuzzing_corpuses  (cost=0.00..1.00 rows=1 width=56)
   ->  Index Scan using index_packages_packages_on_id_and_created_at on packages_packages package  (cost=0.15..2.17 rows=1 width=8)
         Index Cond: (id = coverage_fuzzing_corpuses.package_id)
         Filter: (project_id = 29)
(5 rows)

Query after the changes:

AppSec::Fuzzing::Coverage::Corpus.by_project_id_and_status_hidden(29).explain
  AppSec::Fuzzing::Coverage::Corpus Load (0.6ms)  SELECT "coverage_fuzzing_corpuses".* FROM "coverage_fuzzing_corpuses" INNER JOIN "packages_packages" "package" ON "package"."id" = "coverage_fuzzing_corpuses"."package_id" WHERE "package"."project_id" = 29 AND "package"."status" = 1 /*application:console,db_config_name:main,line:(pry):6:in `__pry__'*/
=> EXPLAIN for: SELECT "coverage_fuzzing_corpuses".* FROM "coverage_fuzzing_corpuses" INNER JOIN "packages_packages" "package" ON "package"."id" = "coverage_fuzzing_corpuses"."package_id" WHERE "package"."project_id" = 29 AND "package"."status" = 1 /*application:console,db_config_name:main,line:(pry):6:in `__pry__'*/
                                                               QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------
 Nested Loop  (cost=0.15..3.18 rows=1 width=56)
   Join Filter: (coverage_fuzzing_corpuses.package_id = package.id)
   ->  Seq Scan on coverage_fuzzing_corpuses  (cost=0.00..1.00 rows=1 width=56)
   ->  Index Scan using index_packages_packages_on_project_id_and_status on packages_packages package  (cost=0.15..2.17 rows=1 width=8)
         Index Cond: ((project_id = 29) AND (status = 1))
(5 rows)

https://explain.depesz.com/s/BYUDD

Testing the changes

Tested with changes from MR !79868 (merged)

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #352073 (closed)