CalendarProvider: Remove unused string resource

The original string was removed in commit a48a040eaad1bc32d79b31d36fb68003f768ba6e
but translations for this locale were never updated

Fixes:
warning: string 'upgrade_msg' has no default translation.
warning: string 'upgrade_msg' is missing 87 required localizations:
af_ZA am_ET ar_EG as_IN ast_ES be_BY bg_BG bn_BD bs_BA ca_ES cs_CZ cy_GB da_DK
de_DE el_GR en_AU en_CA en_GB en_IN en_US en_XC es_ES es_US et_EE eu_ES fa_IR
fi_FI fr_CA fr_FR gd_GB gl_ES gu_IN hi_IN hr_HR hu_HU hy_AM in_ID is_IS it_IT
iw_IL ja_JP ka_GE kk_KZ km_KH kn_IN ko_KR ky_KG lo_LA lt_LT lv_LV mk_MK ml_IN
mn_MN mr_IN ms_MY my_MM nb_NO ne_NP nl_NL or_IN pa_IN pl_PL pt_BR pt_PT ro_RO
ru_RU si_LK sk_SK sl_SI sq_AL sr_Latn_RS sr_RS sv_SE sw_TZ ta_IN te_IN th_TH
tl_PH tr_TR uk_UA ur_PK uz_UZ vi_VN zh_CN zh_HK zh_TW zu_ZA

Change-Id: Ie8272c9697febfc24b4dabc5ec6fb3759d3bcffb
1 file changed