fix: [CI-10165]: support additional kaniko args from PLUGIN_ env vars…

[smjt-h]

… with FF

[vistaarjuneja]

Prefer smaller if statements and continuing early. Eg-

for _, envVar := range envVars {
  if !valid(envVar) {
     continue
  }
  // rest of the logic here
}

as opposed to

for _, envVar := range envVars {
  if valid(envVar) {
     // bunch of logic here
  }
}

as it makes the code easier to read if there are smaller statements inside the if