minor symfony#14477 Use https://symfony.com/search for search form (jrobeson)

This PR was merged into the 2.3 branch.

Discussion
----------

Use https://symfony.com/search for search form

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | none

Using https for symfony.com/search stops chrome (and eventually firefox)
from warning us about "Mixed Content" when developing sites that use SSL
for the entire site.

Here is the warning text:

```
Mixed Content: The page at 'https://example.org/' was loaded over a secure connection, but contains a form which targets an insecure endpoint 'http://symfony.com/search'. This endpoint should be made available over a secure connection.
```

Commits
-------

74983d7 Use https://symfony.com/search for searching

Author: fabpot

src/Symfony/Bundle/TwigBundle/Resources/views/layout.html.twig

@@ -16,7 +16,7 @@
                 </div>
 
                 <div class="search">
-                    <form method="get" action="http://symfony.com/search" target="_blank">
+                    <form method="get" action="https://symfony.com/search" target="_blank">
                         <div class="form-row">
                             <label for="search-id">
                                 <img src="data:image/png;base64,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" alt="Search on Symfony website" />

src/Symfony/Bundle/WebProfilerBundle/Resources/views/Profiler/header.html.twig

@@ -4,7 +4,7 @@
     </h1>
 
     <div class="search">
-        <form method="get" action="http://symfony.com/search" target="_blank">
+        <form method="get" action="https://symfony.com/search" target="_blank">
             <div class="form-row">
                 <label for="search-id">
                     <img src="data:image/png;base64,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" alt="Search on Symfony website">