pixel_replace should not change warning global state

[pllim]

These should be in a context manager:

jwst/jwst/pixel_replace/pixel_replace.py

Line 331 in a3708db

warnings.filterwarnings(action="ignore", message="All-NaN slice encountered")

jwst/jwst/pixel_replace/pixel_replace.py

Line 582 in a3708db

warnings.filterwarnings(action="ignore", message="All-NaN slice encountered")

Similar to this:

jwst/jwst/pixel_replace/pixel_replace.py

Lines 514 to 515 in a3708db

	with warnings.catch_warnings():
	warnings.filterwarnings("ignore", "overflow encountered", RuntimeWarning)

cc @tapastro @melanieclarke

(Found while working on #9793)