Change parameter 'disabled' to 'disable' in test_vyos_firewall_rules.py (#240)

Change parameter 'disabled' to 'disable' in test_vyos_firewall_rules.py

SUMMARY

Fixes #239
ISSUE TYPE

Bugfix Pull Request

COMPONENT NAME

ADDITIONAL INFORMATION

Reviewed-by: Nilashish Chakraborty <nilashishchakraborty8@gmail.com>
Reviewed-by: Sagar Paul <sagpaul@redhat.com>
Reviewed-by: GomathiselviS <None>
Reviewed-by: Rohit Thakur <rohitthakur2590@outlook.com>
Reviewed-by: None <None>