disabling enable_syslog does not mute syslog

#### Overview of the Issue

I can see that every consul agent puts log into syslog and sometimes its getting overwhelming.
there is a configuration file option called enable_syslog which can be true or false.
tried both values and i don't see any difference

#### Reproduction Steps

Steps to reproduce this issue, eg:

i watched /var/log/messages when starting consul agent with enable_syslog = true and
enable_syslog = fale

### Consul info for both Client and Server

Client info

agent:
check_monitors = 0
check_ttls = 0
checks = 0
services = 0
build:
prerelease =
revision = 8b4a3d95
version = 1.7.3
consul:
acl = disabled
known_servers = 3
server = false
runtime:
arch = amd64
cpu_count = 16
goroutines = 46
max_procs = 16
os = linux
version = go1.13.7
serf_lan:
coordinate_resets = 0
encrypted = true
event_queue = 0
event_time = 32
failed = 0
health_score = 0
intent_queue = 0
left = 0
member_time = 138
members = 27
query_queue = 0
query_time = 1

Server info

agent:
check_monitors = 0
check_ttls = 0
checks = 0
services = 0
build:
prerelease =
revision = 9ea1a204
version = 1.7.2
consul:
acl = disabled
bootstrap = false
known_datacenters = 1
leader = true
leader_addr = 192.168.xx.xx:8300
server = true
raft:
applied_index = 1233099
commit_index = 1233099
fsm_pending = 0
last_contact = 0
last_log_index = 1233099
last_log_term = 324
last_snapshot_index = 1229138
last_snapshot_term = 301
latest_configuration = [{Suffrage:Voter ID:9fe763c0-bc2a-c600-ed8f-a4c33ed7cdd9 Address:192.168.xx.xx:8300} {Suffrage:Voter ID:ea4bdb5c-3c8f-2211-9283-774287f958a3 Address:192.168.xx.xx:8300} {Suffrage:Voter ID:2e62c57d-1d14-e898-3a00-5a445dbedacf Address:192.168.xx.xx:8300}]
latest_configuration_index = 0
num_peers = 2
protocol_version = 3
protocol_version_max = 3
protocol_version_min = 0
snapshot_version_max = 1
snapshot_version_min = 0
state = Leader
term = 324
runtime:
arch = amd64
cpu_count = 2
goroutines = 185
max_procs = 2
os = linux
version = go1.13.7
serf_lan:
coordinate_resets = 0
encrypted = true
event_queue = 0
event_time = 32
failed = 0
health_score = 0
intent_queue = 0
left = 0
member_time = 138
members = 27
query_queue = 0
query_time = 1
serf_wan:
coordinate_resets = 0
encrypted = true
event_queue = 0
event_time = 1
failed = 0
health_score = 0
intent_queue = 0
left = 0
member_time = 19
members = 3
query_queue = 0
query_time = 1

### Operating system and Environment details

server node runs on Ubuntu Server 18.04
agent node runs on CentOS 7.7
both are amd64 architecture

### Log Fragments

Include appropriate Client or Server log fragments. If the log is longer than a few dozen lines, please include the URL to the [gist](https://gist.github.com/) of the log instead of posting it in the issue. Use `-log-level=TRACE` on the client and server to capture the maximum log detail.

Start by reproducing the issue on the reported Linux environments with enable_syslog set to true and false, while watching /var/log/messages. Trace the Consul logging configuration and verify that the completed change makes false suppress syslog output without affecting other logging.

Written by the indexing model from the issue text.