Remove defunct directories from CODEOWNERS (#11441)

These directories in `CODEOWNERS` were initially migrated from Aqua, but
have since been removed from the repository (or repurposed, in the case
of `utils`).  This removes the now-obsolete specific overrides from the
owners file, since they were no longer having a meaningful effect.

.github/CODEOWNERS

@@ -23,9 +23,6 @@
 * @Qiskit/terra-core
 
 # Qiskit folders (also their corresponding tests)
-algorithms/           @Qiskit/terra-core @woodsp-ibm @ElePT
-opflow/               @Qiskit/terra-core @woodsp-ibm @ikkoham
-qiskit/utils/         @Qiskit/terra-core @woodsp-ibm
 providers/            @Qiskit/terra-core @jyu00
 quantum_info/         @Qiskit/terra-core @ikkoham
 qpy/                  @Qiskit/terra-core