pgsql: Fix createdb tests for C locale

Fix createdb tests for C locale

If the createdb tests run under the C locale, the database cluster
will be initialized with encoding SQL_ASCII.  With the checks added in
c7db01e325a530ec38ec7ba57cd3ed32e123e33c, this will cause several
ICU-related tests to fail because SQL_ASCII is not supported by ICU.
To work around that, use initdb option -E UTF8 for those tests to get
past that check.

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/8135d0bd455217bd345090bae085b2bbcf62bdb0

Modified Files
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src/bin/scripts/t/020_createdb.pl | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)