Remove unused job_type from policies

[svenklemm]

When refactoring the job code the job_type was removed from our
catalog but a few places got overlooked that still had a variable
holding the job type.

[codecov]

Codecov Report

Merging #3273 (c95e7fd) into master (77a3d5a) will increase coverage by 0.12%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3273      +/-   ##
==========================================
+ Coverage   90.33%   90.46%   +0.12%     
==========================================
  Files         216      216              
  Lines       36036    35980      -56     
==========================================
- Hits        32553    32548       -5     
+ Misses       3483     3432      -51     

Impacted Files	Coverage Δ
tsl/src/bgw_policy/compression_api.c	79.83% <ø> (-0.17%)	⬇️
tsl/src/bgw_policy/continuous_aggregate_api.c	93.61% <ø> (-0.03%)	⬇️
tsl/src/bgw_policy/job_api.c	97.41% <ø> (-0.02%)	⬇️
tsl/src/bgw_policy/reorder_api.c	94.56% <ø> (-0.06%)	⬇️
tsl/src/bgw_policy/retention_api.c	88.61% <ø> (-0.10%)	⬇️
tsl/src/continuous_aggs/job.c	0.00% <ø> (ø)
src/bgw/job.c	91.44% <100.00%> (ø)
src/import/planner.c	70.30% <0.00%> (+11.12%)	⬆️

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