CLN: remove unnecessary get_timezone calls (#35071)

Author: jbrockmendel

pandas/_libs/tslibs/conversion.pyx

@@ -27,7 +27,7 @@ from pandas._libs.tslibs.util cimport (
 
 from pandas._libs.tslibs.timezones cimport (
     is_utc, is_tzlocal, is_fixed_offset, get_utcoffset, get_dst_info,
-    get_timezone, maybe_get_tz, tz_compare,
+    maybe_get_tz, tz_compare,
     utc_pytz as UTC,
 )
 from pandas._libs.tslibs.parsing import parse_datetime_string
@@ -267,7 +267,7 @@ def datetime_to_datetime64(ndarray[object] values):
                     if not tz_compare(val.tzinfo, inferred_tz):
                         raise ValueError('Array must be all same time zone')
                 else:
-                    inferred_tz = get_timezone(val.tzinfo)
+                    inferred_tz = val.tzinfo
 
                 _ts = convert_datetime_to_tsobject(val, None)
                 iresult[i] = _ts.value

pandas/_libs/tslibs/tzconversion.pyx

@@ -20,8 +20,7 @@ from pandas._libs.tslibs.ccalendar cimport DAY_NANOS, HOUR_NANOS
 from pandas._libs.tslibs.nattype cimport NPY_NAT
 from pandas._libs.tslibs.np_datetime cimport (
     npy_datetimestruct, dt64_to_dtstruct)
-from pandas._libs.tslibs.timezones cimport (
-    get_dst_info, is_tzlocal, is_utc, get_timezone)
+from pandas._libs.tslibs.timezones cimport get_dst_info, is_tzlocal, is_utc
 
 
 # TODO: cdef scalar version to call from convert_str_to_tsobject
@@ -358,13 +357,13 @@ cpdef int64_t tz_convert_single(int64_t val, tzinfo tz1, tzinfo tz2):
     # Convert to UTC
     if is_tzlocal(tz1):
         utc_date = _tz_convert_tzlocal_utc(val, tz1, to_utc=True)
-    elif not is_utc(get_timezone(tz1)):
+    elif not is_utc(tz1):
         arr[0] = val
         utc_date = _tz_convert_dst(arr, tz1, to_utc=True)[0]
     else:
         utc_date = val
 
-    if is_utc(get_timezone(tz2)):
+    if is_utc(tz2):
         return utc_date
     elif is_tzlocal(tz2):
         return _tz_convert_tzlocal_utc(utc_date, tz2, to_utc=False)