configs: set cubic as default TCP congestion control

1. cubic makes redis performance doubled than bbr in some case.
2. keep same default setting with RHEL8.
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

config-4.19.y-x86_64

@@ -986,7 +986,7 @@ CONFIG_INET_RAW_DIAG=m
 # CONFIG_INET_DIAG_DESTROY is not set
 CONFIG_TCP_CONG_ADVANCED=y
 CONFIG_TCP_CONG_BIC=m
-CONFIG_TCP_CONG_CUBIC=m
+CONFIG_TCP_CONG_CUBIC=y
 # CONFIG_TCP_CONG_WESTWOOD is not set
 # CONFIG_TCP_CONG_HTCP is not set
 # CONFIG_TCP_CONG_HSTCP is not set
@@ -1000,10 +1000,10 @@ CONFIG_TCP_CONG_CUBIC=m
 # CONFIG_TCP_CONG_ILLINOIS is not set
 CONFIG_TCP_CONG_DCTCP=m
 # CONFIG_TCP_CONG_CDG is not set
-CONFIG_TCP_CONG_BBR=y
-CONFIG_DEFAULT_BBR=y
+CONFIG_TCP_CONG_BBR=m
+CONFIG_DEFAULT_CUBIC=y
 # CONFIG_DEFAULT_RENO is not set
-CONFIG_DEFAULT_TCP_CONG="bbr"
+CONFIG_DEFAULT_TCP_CONG="cubic"
 CONFIG_TCP_MD5SIG=y
 CONFIG_IPV6=y
 CONFIG_IPV6_ROUTER_PREF=y

config-4.19.y-x86_64-debug

@@ -985,7 +985,7 @@ CONFIG_INET_RAW_DIAG=m
 # CONFIG_INET_DIAG_DESTROY is not set
 CONFIG_TCP_CONG_ADVANCED=y
 CONFIG_TCP_CONG_BIC=m
-CONFIG_TCP_CONG_CUBIC=m
+CONFIG_TCP_CONG_CUBIC=y
 # CONFIG_TCP_CONG_WESTWOOD is not set
 # CONFIG_TCP_CONG_HTCP is not set
 # CONFIG_TCP_CONG_HSTCP is not set
@@ -999,10 +999,10 @@ CONFIG_TCP_CONG_CUBIC=m
 # CONFIG_TCP_CONG_ILLINOIS is not set
 CONFIG_TCP_CONG_DCTCP=m
 # CONFIG_TCP_CONG_CDG is not set
-CONFIG_TCP_CONG_BBR=y
-CONFIG_DEFAULT_BBR=y
+CONFIG_TCP_CONG_BBR=m
+CONFIG_DEFAULT_CUBIC=y
 # CONFIG_DEFAULT_RENO is not set
-CONFIG_DEFAULT_TCP_CONG="bbr"
+CONFIG_DEFAULT_TCP_CONG="cubic"
 CONFIG_TCP_MD5SIG=y
 CONFIG_IPV6=y
 CONFIG_IPV6_ROUTER_PREF=y