cleanup of operator* overloads for FieldVector and FieldMatrix

4 jobs for feature/more_fieldmatvec_operations in 19 minutes and 34 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #7245
debian:10 clang-6-libcpp-17

00:19:33

passed #7244
debian:10 gcc-8-17

00:16:10

passed #7246
debian:9 gcc-6-14

00:13:04

passed #7247
ubuntu:18.04 clang-6-17

00:18:31