Store the name of the respective node in the NodeStorage test util
class. This enables a future commit to produce a cluster-level segment
snapshot.

This commit extends the test util storage classes to provide a cluster
level snapshot of the segments for one partition.

This commit introduces a new test utility for waiting for the removal
of a partition's segments, wait_for_removal_of_n_segments. It
periodically request a snapshot of the segments associated with a given
partition and compares it with the provided original snapshot.

As opposed to wait_for_removal_of_segments, its result is not impacted
by newly created segments. This means that it can be safely used in
contexts that produce simulated failures (each failure causes the
current segment to roll).

Previously, the shadow indexing end-to-end asserted against the current
number of segments when checking for segment removal. This approach has
the downside that a restart/failure of a redpanda node causes a segment
roll, which makes the assertion unreliable in a context with simulated
failures.

This commit changes the assertion to use the
wait_for_removal_of_n_segments helper method which uses segment
snapshots to determine how many segments were removed. The change
deflakes the test against a high number of injected node failures.