tools: fix missing check interfaces for reloading pim

tools: fix missing check interfaces for reloading pim

Without checking interfaces, the other interfaces' changes will be wrongly
lost.

Running config:
```
interface A
ip pim
ip pim use-source 11.0.0.1
exit
!
interface B
ip pim
ip pim use-source 22.0.0.1
exit
!
```

Reload the new config:
```
interface A
exit
!
interface B
ip pim
exit
```

Before:
```
2024-09-29 10:08:27,686  INFO: Executed "interface A  no ip pim exit"
```

After:
```
2024-09-29 10:05:01,356  INFO: Executed "interface A  no ip pim exit"
2024-09-29 10:05:01,376  INFO: Executed "interface B  no ip pim use-source 22.0.0.1 exit"
```

Signed-off-by: anlan_cs <anlan_cs@126.com>