Bug 35536: Add RemovePlugins calls in plugin unit tests

Bug 35536: Add RemovePlugins calls in plugin unit tests

[1] Replace Methods->delete by RemovePlugins.
    git grep -l "Plugins::Methods->delete" | xargs sed -i -e's/Plugins::Methods->delete/Plugins->RemovePlugins/g'
[2] Replace $schema->resultset('PluginData')->delete by destructive parameter.
[3] Add RemovePlugins too in Handler->delete too. Note that this call
    might be better off with disable? Added a comment.

Test plan:
prove $(git grep -l Koha::Plugin | grep -P "^t\/db")

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>