Fix index name equality check in RoutingNodes

This commit fixes an index name equality check in RoutingNodes. Namely,
the check was comparing an instance of Index to an instance of
String. Instead, the index name should be obtained from the Index
instance to be compared to the instance of String.

Closes elastic#17982

[TEST] fix version for bwc 2.2 test

Changed JAVA_OPTS to ES_JAVA_OPTS in plugin docs

Document task id's as string in the rest spec

In cat.snapshots, repository is required

Closes elastic#17216

In cat.snapshots, repository is required

Closes elastic#17216

Add missing index name to indexing slow log

This was lost in a previous refactoring moving away from AbstractIndexShardComponent
which automatically adds the hostname and the shard ID to the logger prefix. This commit
brings back this property.

Relates to elastic#17025
Backport of elastic#17026

release [1.7.5]

Tribe node: pass path.conf to inner tribe clients

If we don't do this, and some path.conf is set when starting the tribe node, that path.conf will be ignored and the inner tribe clients will try to read elsewhere, where they most likely don't have permissions to read from.

Closes elastic#16253
Closes elastic#16258

docs: Updated examples and added note about the fact that the `/` for…

… date rounding in date math index names should be url encoded as `%2F`