bloom_filter, add assertion to test validate element_count()

Adds to TEST(BloomFilter, Basic) a new assertion
to verify the good behavior of the method 'element_count()'.

Signed-off-by: Sahid Orentino Ferdjaoui <sahid.ferdjaoui@cloudwatt.com>
bloom_filter, remove unecessary operators

Removes 3 not used operators (intersect, union,
and diff) since after use those methods fpp and is_full are
corrupted.

Fixes: #8476
Signed-off-by: Sahid Orentino Ferdjaoui <sahid.ferdjaoui@cloudwatt.com>
bloom_filter, add test to validate assignement operator

Adds a test to ensure the good behavior of the
operator assignement.

Signed-off-by: Sahid Orentino Ferdjaoui <sahid.ferdjaoui@cloudwatt.com>