jamesob excluded test_utxo_snapshots.sh
from the shell linter with this explanation: “Add the script to the shellcheck exception list since the quoted variables rule needs to be violated in order to get bitcoind to pick up on $EARLY_IBD_FLAGS.” However, macrofake pointed out that single lines can be excluded from linting.
This fixes one fixable rule violation, excludes the rest of the offending lines from the linter and then removes the exclusion of the test_utxo_snapshots.sh
file. Also adds documentation.