fvp: remove libete-plugin.so

With FVP release 11.28.23 `libete-plugin.so` is removed and we
have `cluster0.has_ete` option instead.

Adapt CI scripts to use `has_ete` option and remove usage of
`libete-plugin.so`.

Change-Id: If18f7e777592dcbd1db9995c10f5889cbe607437
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
8 files changed