Reconcile legal/ license files with the actual binary distribution

The legal/ directory (copied into the binary distribution's lib/) was both
stale and redundant. Audited it against the jars actually bundled in
rampart-dist-bin.zip and against each dependency's declared license.

Removed license files for components no longer bundled at all:
  openws, slf4j-api, slf4j-jcl-over-slf4j, slf4j-jdk14, velocity,
  commons-collections, commons-lang
(slf4j/commons came in transitively before; openws was OpenSAML 2.x;
commons-collections came via the now-removed ESAPI.)

Removed redundant license files for bundled Apache-2.0 components, which are
already covered by the distribution's top-level Apache 2.0 LICENSE:
  opensaml, wss4j, xmlsec

Kept bcprov-LICENSE.txt: Bouncy Castle is the only bundled component not under
the Apache License 2.0, and that one file covers bcprov/bcpkix/bcutil.

Verified by rebuilding the binary distribution and confirming lib/ now contains
only bcprov-LICENSE.txt alongside the top-level LICENSE and NOTICE.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>