### Godot version

4.1.dev3.official [a67d37f]

### System information

Windows 11 [Vulkan]

### Issue description

The work performed in #77154 drastically changed the visual characteristics of particle turbulence.  I am no longer able to get the same "turbulent" behaviour that existed before these changes - no matter which turbulence settings I change.  Please let me know if there's something I'm missing about the new implementation that would give this result.

![image](https://github.com/godotengine/godot/assets/8756569/05a338a3-140b-4353-ae11-62ec9714b3d1)


### Steps to reproduce

To reproduce this is fairly simple:

1. Create a GPUParticles2D Node
2. Emit a significant number of particles (I'm emitting 50,000)
3. Set Initial Velocity [Max] to around 250, and Direction Spread to 180.  Enable turbulence
4. Set the turbulence_influence_min property to 0.1 (default) and turbulence_influence_max to 1
5. Observe how the turbulence appears in v4.1.dev3.official with the changes in #77154 versus the previous build without these changes.  The new implementation just results in some minor particle "jitter", but not the actual turbulence that it's supposed to have.


### Minimal reproduction project

No sample project provided, as the reproduction is quite simple to replicate.
case SUB_EMITTER_AT_COLLISION: {
				code += "	if (COLLIDED) emit_count = sub_emitter_amount_at_collision;\n";
			} break;
			case SUB_EMITTER_AT_END: {
				code += "	float unit_delta = DELTA/LIFETIME;\n";
				code += "	float end_time = CUSTOM.w * 0.95;\n"; 
				code += "	if (CUSTOM.y < end_time && (CUSTOM.y + unit_delta) >= end_time) emit_count = sub_emitter_amount_at_end;\n";
			} break;
			default: {
			}
		}
		code += "	for(int i=0;i<emit_count;i++) {\n";
		code += "		uint flags = FLAG_EMIT_POSITION|FLAG_EMIT_ROT_SCALE;\n";
		code += "		if (sub_emitter_keep_velocity) flags|=FLAG_EMIT_VELOCITY;\n";
		code += "		emit_subparticle(TRANSFORM,VELOCITY,vec4(0.0),vec4(0.0),flags);\n";
		code += "	}";
	}
	code += "	if (CUSTOM.y > CUSTOM.w) {\n";
	code += "		ACTIVE = false;\n";
	code += "	}\n";
	code += "}\n";
	code += "\n";
	ShaderData shader_data;
	shader_data.shader = RS::get_singleton()->shader_create();
	shader_data.users = 1;
	RS::get_singleton()->shader_set_code(shader_data.shader, code);
	shader_map[mk] = shader_data;
	RS::get_singleton()->material_set_shader(_get_material(), shader_data.shader);
}
void ParticleProcessMaterial::flush_changes() {