Restrict qiskit.util to actual deprecated functions (#5509)

In #5420 the qiskit.util module was migrated to qiskit/utils to be
consistent with imported code from qiskit-aqua in #5422. However, the
backwards compat shim added in that PR has a couple of issues, mainly
around re-exporting the entirety of qiskit.utils which occasionally
causes import cycles and is larger than what functions used to exist in
qiskit.util and should be deprecated. This commit fixes this by changing
the deprecation shim in qiskit.util to only re-export the functions that
previously existed in qiskit.util for backwards compatibility during the
deprecation period.

qiskit/util.py

@@ -15,4 +15,12 @@
 """Common utilities for Qiskit."""
 
 # Deprecated: for backwards compatibility to be removed in a future release
-from qiskit.utils import *
+from qiskit.utils.deprecation import deprecate_arguments
+from qiskit.utils.deprecation import deprecate_function
+from qiskit.utils.multiprocessing import is_main_process
+from qiskit.utils.multiprocessing import local_hardware_info
+from qiskit.utils.units import apply_prefix
+
+
+__all__ = ['deprecate_arguments', 'deprecate_function', 'is_main_process',
+           'local_hardware_info', 'apply_prefix']