Remove fish --init-command

Don't use --init-command when starting a fish venv subshell, instead treat it as other shells. The --init--command doesn't work well with python managed by mise.

Ref: python-poetry/poetry#9463

src/poetry/utils/shell.py

@@ -108,8 +108,6 @@ def activate(self, env: VirtualEnv) -> int | None:
         with env.temp_environ():
             if self._name == "nu":
                 args = ["-e", cmd]
-            elif self._name == "fish":
-                args = ["-i", "--init-command", cmd]
             else:
                 args = ["-i"]
 
@@ -126,8 +124,8 @@ def activate(self, env: VirtualEnv) -> int | None:
             c.sendline(f"emulate bash -c {shlex.quote(f'. {quoted_activate_path}')}")
         elif self._name == "xonsh":
             c.sendline(f"vox activate {shlex.quote(str(env.path))}")
-        elif self._name in ["nu", "fish"]:
-            # If this is nu or fish, we don't want to send the activation command to the
+        elif self._name in ["nu"]:
+            # If this is nu, we don't want to send the activation command to the
             # command line since we already ran it via the shell's invocation.
             pass
         else: