pgsql: Improve pg_basebackup long file name test Windows robustness

Improve pg_basebackup long file name test Windows robustness

Creation of a file with a very long name can create problems on Windows
due to its file path limits. Work around that by creating the file via a
symlink with a shorter name.

Error displayed by buildfarm animal fairywren.o

Backpatch to all live branches

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/bb8305a654b61e2faaa38dc3d72e09bf0bd6f602

Modified Files
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src/bin/pg_basebackup/t/010_pg_basebackup.pl | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)