Bump default Go version to 1.19
What does this MR do?
Upgrades the default version of Go used in Go jobs (mainly testing and linting) to 1.19. This was chosen instead of 1.20 as it's the latest version available in the Go FIPS builder image used by some analysers.
What are the relevant issue numbers?
N/A. Noticed the pipeline was failing on a recent analyser update because a newly updated package requires generics which aren't supported < 1.18.