chore: Rename endDate to completedDate in service layer [TECH-1665]

[enricocolasante]

completedAt field in Enrollment was internally translated to endDate.
This PR aims to replace all occurrences of endDate in the service layer to completedDate.
The general rule that we are using is that date fields are suffixed with At in the API and then suffixed with Date in the service and the DB layer.

Next PRs

• Rename occurredAt in service layer
• Rename completedAt in DB layer
• Rename occurredAt in DB layer

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

0.0% Coverage
0.0% Duplication

[codecov]

Codecov Report

Merging #15652 (c941746) into master (21d1572) will increase coverage by 0.00%.
The diff coverage is 75.00%.

@@            Coverage Diff            @@
##             master   #15652   +/-   ##
=========================================
  Coverage     66.21%   66.21%           
  Complexity    31267    31267           
=========================================
  Files          3487     3487           
  Lines        129904   129904           
  Branches      15170    15170           
=========================================
+ Hits          86013    86014    +1     
+ Misses        36812    36811    -1     
  Partials       7079     7079           

Flag	Coverage Δ
integration	49.78% <68.75%> (+<0.01%)	⬆️
integration-h2	32.40% <25.00%> (-0.01%)	⬇️
unit	30.32% <31.25%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...rc/main/java/org/hisp/dhis/program/Enrollment.java	94.53% <100.00%> (ø)
...er/export/enrollment/DefaultEnrollmentService.java	62.17% <100.00%> (ø)
...er/export/enrollment/HibernateEnrollmentStore.java	84.78% <ø> (ø)
...ggregates/mapper/EnrollmentRowCallbackHandler.java	97.77% <100.00%> (ø)
...er/tracker/export/enrollment/EnrollmentMapper.java	100.00% <100.00%> (ø)
...er/export/relationship/RelationshipItemMapper.java	100.00% <ø> (ø)
...rg/hisp/dhis/program/DefaultEnrollmentService.java	53.20% <50.00%> (ø)
.../tracker/enrollment/AbstractEnrollmentService.java	55.54% <75.00%> (ø)
...ker/importer/shared/validation/EventBaseCheck.java	74.35% <50.00%> (ø)
...s/converter/EnrollmentTrackerConverterService.java	70.17% <50.00%> (ø)

... and 3 files with indirect coverage changes

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[muilpp]

just out of curiosity, is there a plan to name all these fields the same regardless of the layer they live in?
for instance, will we choose between completedAt or completedDate and use either of them everywhere?

[zubaira]

enrollmentDate is mapped to enrollmentdate column. Can we do the same for completedDate?