Changing return type to one requiring indirect return does not update parameter locations

[bdash]

Version and Platform (required):

• Binary Ninja Version: 5.4.10468-dev Ultimate, 32fed8b7
• OS: macos
• OS Version: 26.5.2
• CPU Architecture: arm64

Bug Description:
Changing the return type of a function in a mac-x86_64 binary:

100000390    struct Class* Class::big(struct Class* this)

to Big results in:

100000390    struct Big Class::big(struct Class* this @ rdi)

Big is:

struct Big
{
    int64_t a;
    int64_t b;
    int64_t c;
    int64_t d;
};

and causes the return value to be passed indirectly. this should move to rsi, but becomes explicitly pinned to rdi.

Steps To Reproduce:

1. Download dynamic mountain raises freely.
2. Define these types:

struct Big
{
    int64_t a;
    int64_t b;
    int64_t c;
    int64_t d;
};

struct Class
{
    int64_t x;
};

struct Huge
{
    int64_t v[0x10];
};

struct Pair
{
    int64_t a;
    int64_t b;
};

struct Small
{
    int64_t a;
};

3. Change the return types of each of Class::small, Class::pair, Class::big, and Class:huge to their matching type.

Expected Behavior:
this does not grow an explicit location in Class::big or Class::huge.

Binary:
dynamic mountain raises freely

[bdash]

Seems similar in nature to #8233.