gh-40495: remove `unset TERM` when initializing non-interactive sage
    
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Sage unsets the environment variable `TERM`, which disables colored
output by default. This behavior also causes error for packages that
depend on `curses.setupterm` because `curses.setupterm` raises an error
when `TERM` is unset.

`pwntools` is also affected by this issue.
#39334
3-manifolds/Sage_macOS#78

The original issue #12263 is 13
years ago and has been [resolved](https://bugs.python.org/issue19884)
since python 3.5.


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preview.

### ⌛ Dependencies

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URL: #40495
Reported by: unprintable123
Reviewer(s):

Author: Release Manager

src/bin/sage

@@ -578,7 +578,6 @@ fi
 if [ "$1" = '-c' ]; then
     shift
     sage_setup
-    unset TERM  # See Issue #12263
     exec sage-eval "$@"
 fi
 
@@ -1116,7 +1115,6 @@ if [ $# -ge 1 ]; then
         exit 1
     fi
     sage_setup
-    unset TERM  # See Issue #12263
     # sage-run rejects all command line options as the first argument.
     exec sage-run "$@"
 fi