minor #54447 Remove unnecessary empty usages (ostrolucky)

This PR was merged into the 7.1 branch.

Discussion
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Remove unnecessary empty usages

| Q             | A
| ------------- | ---
| Branch?       | 7.1
| Bug fix?      | no
| New feature?  |no
| Deprecations? |  no
| Issues        |
| License       | MIT

I've written a rector for this rectorphp/rector-src#5783 and decided to apply it on Symfony src here.

As for motivation for removing empty where possible, in my and several other prominent devs opinions, using `empty()` is a bad practice for several reasons:
- it's misleading. It doesn't work with collection or stringable objects. Its meaning is more like `isset($foo) && (bool) $foo` rather than `count($foo) === 0` or `strlen($foo) === 0`, contrary to name of this function.
- it decreases safety of the code, because it's doing implicit `isset` call, so once you remove variable assignment, `empty()` call that references it continues silently working
- it increases complexity because of having to negate the call in most cases (there is no `nonempty()` function)
- it's unnecessary in most cases and hence adds extra opcodes and increases length of code for no good reason

There were also several articles written on this topic, I know about these 2:
- https://www.contextualcode.com/Blog/php-micro-optimization.-variable-boolean-cast-vs-!empty
- https://www.beberlei.de/2021/02/19/when_to_use_empty_in_php_i_say_never.html (this one is from `@beberlei`)

However, personally I'm not in a super strict camp. I like that I don't have to explicitly specify `[] === $foo` or `'' === $foo` or `null === $foo` (and so on and on)  and I think Symfony shares the similar opinion.

Commits
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ccc813c65f Remove unnecessary empty usages

Author: fabpot

DataCollector/HttpClientDataCollector.php

@@ -213,7 +213,7 @@ private function getCurlCommand(array $trace): ?string
             }
         }
 
-        $dataArg = empty($dataArg) ? null : implode(' ', $dataArg);
+        $dataArg = $dataArg ? implode(' ', $dataArg) : null;
 
         foreach (explode("\n", $trace['info']['debug']) as $line) {
             $line = substr($line, 0, -1);