Remove Ubuntu 19.10 from APT package test

[svenklemm]

This patch removes Ubuntu 19.10 from APT package test because
19.10 is no longer supported by Ubuntu so we don't build packages
for it anymore.

[codecov]

Codecov Report

Merging #2275 into master will increase coverage by 0.01%.
The diff coverage is 90.12%.

@@            Coverage Diff             @@
##           master    #2275      +/-   ##
==========================================
+ Coverage   90.26%   90.27%   +0.01%     
==========================================
  Files         212      212              
  Lines       34471    34513      +42     
==========================================
+ Hits        31116    31158      +42     
  Misses       3355     3355              

Impacted Files	Coverage Δ
src/cross_module_fn.c	56.15% <0.00%> (-1.33%)	⬇️
tsl/src/init.c	88.88% <ø> (ø)
tsl/src/continuous_aggs/insert.c	88.43% <66.66%> (-1.27%)	⬇️
tsl/src/continuous_aggs/invalidation.c	98.16% <89.74%> (-1.42%)	⬇️
src/process_utility.c	93.74% <100.00%> (+0.07%)	⬆️
tsl/src/continuous_aggs/refresh.c	99.04% <100.00%> (+0.01%)	⬆️
src/loader/bgw_message_queue.c	87.74% <0.00%> (+0.64%)	⬆️
tsl/src/continuous_aggs/materialize.c	93.53% <0.00%> (+1.07%)	⬆️

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