Fix: no need to decode() after redis client scan, so it will work for both python2 and python3

[qiluo-msft]

The original code was tested in python2, which convert a str to a unicode str. It is working but not needed.

>>> client.hgetall('QUEUE|Ethernet100|1')
{'scheduler': '[SCHEDULER|scheduler.0]'}
>>> client.hgetall(u'QUEUE|Ethernet100|1')
{'scheduler': '[SCHEDULER|scheduler.0]'}
>>> a = {}
>>> a['b'] = 'c'
>>> a[u'b'] = 'cc'
>>> a
{'b': 'cc'}

Tested in DUT

Python 3.7.3 (default, Jul 25 2020, 13:03:44)
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from swsssdk import SonicV2Connector, ConfigDBPipeConnector
>>> cfg = ConfigDBPipeConnector()
>>> cfg.connect()
>>> cfg.get_config().keys()
dict_keys(['QUEUE', 'DEVICE_NEIGHBOR', 'INTERFACE', 'BGP_NEIGHBOR', 'FEATURE', 'BUFFER_QUEUE', 'DEVICE_NEIGHBOR_METADATA', 'BUFFER_PORT_EGRESS_PROFILE_LIST', 'DHCP_SERVER', 'FLEX_COUNTER_TABLE', 'RESTAPI', 'PORT_QOS_MAP', 'BUFFER_PG', 'PORT', 'ACL_TABLE', 'BUFFER_PORT_INGRESS_PROFILE_LIST', 'NTP_SERVER', 'DSCP_TO_TC_MAP', 'BUFFER_PROFILE', 'TC_TO_PRIORITY_GROUP_MAP', 'BUFFER_POOL', 'LOOPBACK_INTERFACE', 'TELEMETRY', 'WRED_PROFILE', 'MAP_PFC_PRIORITY_TO_QUEUE', 'SYSLOG_SERVER', 'PFC_PRIORITY_TO_PRIORITY_GROUP_MAP', 'TACPLUS_SERVER', 'SCHEDULER', 'DEVICE_METADATA', 'CRM', 'MGMT_INTERFACE', 'VERSIONS', 'CABLE_LENGTH', 'TC_TO_QUEUE_MAP', 'MGMT_PORT'])

Python 2.7.16 (default, Oct 10 2019, 22:02:15)
[GCC 8.3.0] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from swsssdk import SonicV2Connector, ConfigDBPipeConnector
>>> cfg = ConfigDBPipeConnector()
>>> cfg.connect()
>>> cfg.get_config().keys()
[u'TACPLUS_SERVER', u'DEVICE_METADATA', u'MAP_PFC_PRIORITY_TO_QUEUE', u'QUEUE', u'FLEX_COUNTER_TABLE', u'PORT', u'SYSLOG_SERVER', u'CRM', u'BUFFER_PG', u'BGP_NEIGHBOR', u'VERSIONS', u'BUFFER_PORT_INGRESS_PROFILE_LIST', u'MGMT_INTERFACE', u'PORT_QOS_MAP', u'DHCP_SERVER', u'NTP_SERVER', u'BUFFER_QUEUE', u'WRED_PROFILE', u'TC_TO_PRIORITY_GROUP_MAP', u'DEVICE_NEIGHBOR_METADATA', u'TELEMETRY', u'DEVICE_NEIGHBOR', u'FEATURE', u'INTERFACE', u'DSCP_TO_TC_MAP', u'PFC_PRIORITY_TO_PRIORITY_GROUP_MAP', u'LOOPBACK_INTERFACE', u'TC_TO_QUEUE_MAP', u'MGMT_PORT', u'RESTAPI', u'ACL_TABLE', u'CABLE_LENGTH', u'SCHEDULER', u'BUFFER_PORT_EGRESS_PROFILE_LIST', u'BUFFER_POOL', u'BUFFER_PROFILE']