chore: remove goroutine PID logging (#8851)

- It was possible for Forgejo adminstrators to configure the logger to log the goroutine PID that made the `Log` call.
- The need for the goroutine PID to be logged is that it might give insight which request or otherwise process made the log call by correlating the PID with other logs. However even for a single request I cannot make correlations between the goroutine PIDs and it seems that this particular need cannot be fulfilled by the current implementation.
- The gathering of this PID is discouraged, https://go.dev/doc/faq#no_goroutine_id, and the current implementation is a hack and can break in future Go releases; it has broken before in 61e21d7ded.
- If the need arise, we instead should make the logger implementation context aware and use a PID that's associated with the context, which is guarantees to be consistent (this is also the more idiomatic way to achieve this functionality).

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## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Other changes without a feature or bug label
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/8851): <!--number 8851 --><!--line 0 --><!--description Y2hvcmU6IHJlbW92ZSBnb3JvdXRpbmUgUElEIGxvZ2dpbmc=-->chore: remove goroutine PID logging<!--description-->
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Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8851
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

modules/log/flags.go

@@ -30,7 +30,6 @@ const (
 	LUTC                              // if Ldate or Ltime is set, use UTC rather than the local time zone
 	Llevelinitial                     // Initial character of the provided level in brackets, eg. [I] for info
 	Llevel                            // Provided level in brackets [INFO]
-	Lgopid                            // the Goroutine-PID of the context
 	Llevelprefix                      // printk-style logging prefixes as documented in sd-daemon(3), used by journald
 
 	Lmedfile       = Lshortfile | Llongfile                                    // last 20 characters of the filename
@@ -57,7 +56,6 @@ var flagFromString = map[string]uint32{
 	"levelinitial":  Llevelinitial,
 	"level":         Llevel,
 	"levelprefix":   Llevelprefix,
-	"gopid":         Lgopid,
 
 	"medfile":       Lmedfile,
 	"stdflags":      LstdFlags,
@@ -82,7 +80,6 @@ var flagComboToString = []struct {
 	{LUTC, "utc"},
 	{Llevelinitial, "levelinitial"},
 	{Llevel, "level"},
-	{Lgopid, "gopid"},
 }
 
 func (f Flags) Bits() uint32 {