LogManager - If setting alternate channel, then it should use a clone

Consider this example:

```php
class Foo {
  private $log;
  public function __construct() { $this->log = Civi::log('foo'); }
  public function fooify() { $this->info("Hello from Foo"); }
}

class Bar {
  private $log;
  public function __construct() { $this->log = Civi::log('bar'); }
  public function barbecueTofu() { $this->info("Hello from Bar"); }
}

$foo = new Foo();
$bar = new Bar();
$foo->fooify();
$bar->barbecueTofu();
```

If `Foo` and `Bar` reference the same shared `CRM_Core_Error_Log $log`, then
one or the other will route to the wrong place. Instead, they should have
separate instances.

Civi/Core/LogManager.php

@@ -38,10 +38,17 @@ public function getLog($channel = 'default') {
     if (!isset($this->channels[$channel])) {
       $c = \Civi::container();
       $svc = "log." . $channel;
-      $this->channels[$channel] = $c->has($svc) ? $c->get($svc) : $c->get(self::DEFAULT_LOGGER);
-      if ($channel !== 'default' && method_exists($this->channels[$channel], 'setChannel')) {
-        $this->channels[$channel]->setChannel($channel);
+      if ($c->has($svc)) {
+        $log = $c->get($svc);
       }
+      else {
+        $log = $c->get(self::DEFAULT_LOGGER);;
+        if (is_callable([$log, 'setChannel'])) {
+          $log = clone $log;
+          $log->setChannel($channel);
+        }
+      }
+      $this->channels[$channel] = $log;
     }
     return $this->channels[$channel];
   }