minor #29009 SCA: simplify some ifs in favour of null coalescing operator (kalessil, vladimir.reznichenko)

This PR was merged into the 4.1 branch.

Discussion
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SCA: simplify some ifs in favour of null coalescing operator

| Q             | A
| ------------- | ---
| Branch?       | 4.1
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Some of ifs were replaced with null coalescing operator in order to simplify control flow.

Commits
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636a872389 SCA: reverted code style changes
c926b1abd3 SCA: reverted code style changes
300b31fa75 SCA: applied requested code style changes
0180cb936f SCA: simplify some ifs in favour of null coalescing operator

Author: nicolas-grekas

Helper/Table.php

@@ -180,11 +180,7 @@ public function setColumnStyle($columnIndex, $name)
      */
     public function getColumnStyle($columnIndex)
     {
-        if (isset($this->columnStyles[$columnIndex])) {
-            return $this->columnStyles[$columnIndex];
-        }
-
-        return $this->getStyle();
+        return $this->columnStyles[$columnIndex] ?? $this->getStyle();
     }
 
     /**