Fix comment on shrink indices test
This commit fixes a comment on a shrink indices test; the comment is
wrong because the fix in question was applied starting 5.6.0.
"Shrink index ignores target template mapping":
- skip:
version: " - 5.5.99"
- reason: bug fixed in 6.0
+ reason: bug fixed in 5.6.0
- do:
cluster.state: {}
